Chris Kadlec stands beside his car at Pere Marquette Beach in Muskegon, Michigan in the summer of 2005. The car, a 1995 Chevy Cavalier, is the backbone of his lake inversion studies and home to his one and only radio, a factory-installed Delco, which has logged stations while travelling across the country for more than six years.

Chris Kadlec began studying the effects of tropospheric lake inversion on FM radio reception in West Michigan in 2002 after noticing some peculiar and abnormal patterns. Over the months and years, the locations changed and the FM dial has changed – formats, call letters, and even tower locations – but the patterns always remained peculiar. Kadlec attempts to study a phenomenon that few others have actively looked into. Hawaiian DXer Sheldon Remington, who is known for receiving mainland stations via tropospheric ducts in the 1980s and 1990s at a distance exceeding 2,300 miles and as far as Manzanillo, Mexico, in excess of 3,400 miles to the southeast, a tropospheric reception record, is among the early few who have shown that ducting over water is a great way to receive radio stations.

Unlike many DXers – hobbyists who attempt to “catch” distant communication signals through atmospheric abnormalities – Kadlec has kept complete logs of all non-local stations received. Many in the hobby have little use for such a log. As stations over the years are received on a number of days, the thrill of the hobby becomes greatly diminished by logging the same stations over and over each day. Instead, many will log a station once when it is first received. Loggings after that count as “relogs,” the term given to a station already received and thus no longer needed in the log.

DXing is a hobby, but studying reception patterns of stations via tropospheric conditions is a science of mesoscale meteorology and physics. As many meteorologists and communication engineers would say, it’s a rather impossible science. Signals cannot be traced with the eye. A distant signal that arrives at one point may have been affected by three different atmospheric abnormalities along its path. Which ones and where they occurred are often impossible to determine. So why bother? Kadlec, 25, has continued logging the same stations each and every day in search of an eventual answer. Receiving the stations is not the thrill. Determining how they reach their final destination is the target and the quest to understand the patterns is the thrill.

The study area

The lake inversion study was conducted in West Michigan’s central coastal region consisting of the cities of Grand Haven, Muskegon, Fremont, and Hart. Logs were compiled over four years in multiple locations spanning from 25 miles inland to the sand dunes and bluffs that line the Lake Michigan shore. The main study location of the summer of 2006 was Grand Haven, a beachside tourist town of about 13,000 directly across the lake from Milwaukee. Locations included in the Grand Haven study ranged from parallel parking beside the beach bordered by tall residentially-developed forested bluffs to the top of a bluff used to monitor duct elevations and heights. Northern stations were logged at the Silver Lake sand dunes near Mears and at Little Sable Point, across from Sheboygan, Wisconsin. The study area was split into four different regions to assist in understanding reception patterns.

Lake Michigan, the world’s fifth largest lake and the only one of the five Great Lakes entirely in the United States, was the focus of the study. Lake Michigan is 118 miles (190 kilometers) wide at its widest point and 307 miles (494 kilometers) long. The lake off the coast near Frankfort, Michigan is 923 feet deep, its deepest point, and averages 279 feet deep. Its height above sea level is currently 577 feet, the same as neighbouring Lake Huron, and fluctuates over time. Fremont, although inland, is exactly halfway between the bottom tip of the lake and the northern tip of the Door Peninsula, the extent of most reception originating from major markets. The 127 miles of water in each direction provides an ideal ground for measuring the strength of signals from the north and south at any given time, often between the Chicago and Green Bay markets. This is a valuable indicator of lake conditions. The northern and southern beach sites, 44 miles apart, are both an equal 107 miles from the markets they target – Grand Haven for the study of Chicago signals and Silver Lake for the study of Green Bay signals. Both of these beach locations are an equal 32 miles from the home site of Fremont.

Patterns in reception and lake-level ducts

Over a period of four years, one would hopefully be able to notice patterns in reception. A set of distant stations may appear suddenly over a hill and be heard like locals for the next fifty miles. Another set of stations may come in only on rainy days. Maybe only on a clear sunny day, but that’s not to be unexpected. All of these stations have one thing in common: Lake Michigan. Conditions over the lake on any given day can assist stations in travelling over 200 miles. On days with long-haul tropospheric ducting (Iowa, Minnesota, and western Wisconsin are most common in this area), any station that reaches the western edge of Lake Michigan via this mode can effectively travel the additional 90 miles across the lake by travelling through a lake-level duct that is so often existing atop the water’s surface. The stations can be received often along the beach with little loss of quality. Stronger openings may produce ducts at different levels that can be received on the beach and atop the dunes or only at a higher level.

In short, there is no easy way to predict conditions. On the clearest sunny summer day, you may turn on your radio and realize things are just rather silent. More often than not though, you will hear something if you know where to look and what to listen for. The best conditions for any activity are always high pressure systems. You may get a spectacular opening during any other given time, but if you’re searching for some good catches, wait for a high pressure system with clear skies. It has been noticed during long-haul tropo events that the expected cross-lake stations often disappear from the dial as stations from more distant locales begin to be heard. The dial becomes eerily silent at a time when dozens of stations would typically be heard loud and clear from Wisconsin and Illinois. The phenomenon appears to be an effect of the upper-level ducts that force lake inversion ducts closer to the lake surface, thus squashing the expected stations. When entering such a duct from a higher or lower elevation, lake inversion reception gradually fades out, the dial becomes silent aside from local stations, and slowly long-distance tropo stations appear.

Know the terrain around you. The most dominant factor in reception in West Michigan is often terrain. A select area of this region surrounding the Muskegon River and Grand River (and everything between) includes a terrain ideal for distant reception assisted by the lake. In this area, there is an absence of the rolling hills – called moraines – so typical to the Midwest glacial environment. Although they may be small, moraines can easily wipe out cross-lake signals. Most signals from Wisconsin, Illinois, and the Upper Peninsula of Michigan are certainly distant. They will hover close to the ground until they hit unfavourable terrain that the signals will then bounce off of back into space. With the absence of moraines in this area, stations that ride the lake ducts at different elevations can easily cross the water and bump into land as it rises where they are then heard by a listener.

Rising elevation and its effect on stations

As with any gradually-rising terrain beside a large body of water, ducts forming over water at select elevations can make reception areas impossible to judge. Lake Michigan’s surface generally sits at an elevation of approximately 577 feet above sea level. From the beach, which in some locations is lined with tall sand dunes of up to 150 or more feet thus blocking reception inland, land elevation gradually increases to around 850-900 feet without significant moraines. A duct 250 feet over Lake Michigan, whatever its vertical reach may be from top to bottom, will likely produce an ideal opening around 750 feet on land. In many cases, this is approximately 20-25 miles inland depending on surrounding terrain such as a river valley or lake. As is normal, due to the curvature of the Earth, distant signals gradually extend into space until they collide with atmospheric conditions that send them back toward Earth. The Earth’s curvature can help extend signals on occasion given the proper conditions. A duct 250 feet above the lake surface will not be heard as effectively at 830 feet as you might imagine (that is, 250 feet above the level of the lake on land). Signals that lose no elevation over water while they are trapped in a duct will almost surely lose elevation, often faster than normal, once over land. The velocity of signal loss over land depends ultimately on the original strength of the signal both over water and at the beach.

The varying height and elevation of ducts over water

Meteorological conditions are often predictable. The possible presence of tropospheric ducts is almost equally predictable, most commonly predicted for DX hobbyists by William Hepburn, a Southern Ontario meteorologist who developed the widely-used Hepburn Tropo Index. The Hepburn Index cannot predict the exact locations of a duct. It cannot predict accurately if there will indeed be a duct at any given time. It simply predicts the locations of atmospheric conditions that are ideal for the production of tropospheric bending. Despite the often accurate nature of the produced maps, since conditions vary greatly over water as compared to land, the Hepburn Index is not so accurate for forecasting conditions over the Great Lakes during the warmer months of the year. Hepburn agrees, stating that “the Tropo Index was primarily designed to catch the longest distance ducts involving higher level inversions and won't catch these shallow lake inversions very well, if at all.” The index does not take into account the constantly-varying water temperatures of Lake Michigan which can assist in producing ducts.

The difference in water temperature and air temperature can produce fog banks that refract signals or trap signals and send them shooting out unpredictably. The temperature difference can also create ducts themselves, either multiple ducts or one large duct that may span a height of several hundred or thousand feet over the water. The vertical height of ducts over the water will often determine how far inland stations will be heard. Understanding the height and locations of ducts is essential to coastal DXing.

A duct with a vertical height of 50 feet will, in most cases, produce signals only within a few miles of Lake Michigan barring any unforeseen coastal conditions such as fog. A signal – whether radio, television, or even cellphone – does not typically travel straight across the lake in a duct. Since signals by nature reflect off surfaces either toward the ground or into space, a signal caught in a duct will in most cases bounce between the top and the bottom of the duct endlessly until there is an opening in the duct. An opening may exist in the middle of the lake if conditions change and the signal will drop from the duct and in some cases bounce off the water below and off the bottom of the duct it originated from until it reaches either land or yet another change in conditions. Whether stations travel a straight line parallel to the water or get caught in a commonly-existing low-level duct with a short vertical height atop the lake surface is unknown. In either case, the signal often falls onto and remains within 50 feet of the surface of the lake. This phenomenon can easily be referred to as the “net effect”.

On many summer days, Lake Michigan produces large ducts several hundred or thousand feet high and sometimes in excess of a hundred miles wide. Such a duct that spans the lake and is several hundred feet from the lake surface to the top of the duct creates spectacular DX conditions. Stations from cross-lake markets such as Chicago, Milwaukee, Green Bay, and Madison will reach the shores of Michigan with the quality of a local station. Stations from specific distances will bounce between the top and bottom of the duct in such a fashion that they refract off the top of the duct hundreds of feet in the air and can be heard with local quality up to 40 miles inland with their only assistance being Lake Michigan. Ducts that are stable during the afternoon and evening hours and do not change in height nor form may assist certain stations in travelling the exact same route throughout the day. DXers will hear these stations far inland but not on the beach.

The net effect

The net effect is best experienced during long-haul tropo, that is, when conditions over land and not just over water cause stations to exceed their normal coverage area sometimes by several hundred miles. While lake inversion ducts are a mesoscale phenomenon, confined to a smaller area, long-haul tropo is more of a synoptic scale phenomenon, covering a larger area. An opening between Des Moines and Milwaukee, not too uncommon, can easily be extended to Muskegon and Grand Haven (but rarely further). Stations that hit the ground in Milwaukee or Chicago ride the lake’s surface unaffected an additional 60-150+ miles across the water, which are then heard on the beach. Whether a similar effect can be used to extend E-Skip, which originates from upper-atmospheric conditions several hundred miles further away, remains unknown due to its sporadic nature.

The net effect can also be seen along coastal locations on the Atlantic Ocean. Cape Cod, Cape May, the Outer Banks, and the south shore of Nova Scotia are ideal places to experience this effect. Reception on both the FM and TV bands is commonly reported by Cape Cod DXer Roy Barstow as originating from Nova Scotia, Maryland, Virginia, and often the Outer Banks of North Carolina, nearly 500 miles away. Florida stations over a thousand miles away have even been reported here during tropospheric ducting over the ocean. On Cape May on the southern tip of New Jersey, DXer Michael Temme-Soifer reports receiving television stations from western North Carolina with only rabbit ears during otherwise dead conditions. The same applied for the FM band during otherwise dead conditions. The coastal area, which regularly pulls in stations in excess of 200 miles away, experiences intense 650 to 700-mile long-range ducts from Nova Scotia producing stations with local-like quality. In addition to ordinary FM stations, lower-powered (195 to 215-watt) Canadian marine weather frequencies can sometimes be heard, yet with few stations between the two locations being heard with similar strength. Such openings are straight-line water paths with very little or no land interrupting their long voyages. This is much the case on Lake Michigan where one side of the lake has multiple major markets and the opposite is far less populated and with fewer interfering locals.

The science of intense cross-lake openings

About ten to twenty times per warm season – typically from late March to mid-October along Lake Michigan – a large, long-lasting, and intensely strong mesoscale-origin opening will be recorded. Sometimes the opening is in one specific direction. Stations from Milwaukee and Green Bay may be received while Chicago is completely absent from the dial. During other times, multiple markets may come in with local quality. Green Bay, Milwaukee, Chicago and everything in between them can be heard loudly with perfect signals. Stations from Madison, on average 160-170 miles away, often are heard strongly during such openings as these stations often reach Lake Michigan at Milwaukee. Rockford, Oshkosh, and the more distant Wausau and Wisconsin Rapids (200+ miles to the northwest) also will be heard on many of these days if the frequency isn’t occupied by a closer station between the two points. Wisconsin Rapids and Wausau are heard more frequently due to their high elevations. For example, stations such as WGLX on 103.3 operate at 100,000 watts at more than 1,200 feet above sea level and the signal falls to Earth over Lake Michigan due to no interfering terrain. The station can reach well inland given the absence of any other stations.

During any cross-lake opening, especially intense ones, effective radiated power makes little difference. A 3,000-watt station 130 miles away will be heard as loudly as a 100,000-watt station 100 miles away. Low-powered stations (LPs) also can be heard at distances of over 100 miles easily at local-quality. The quality of the signal is often determined by what the station strength is at the moment it reaches the water. If a 50-watt station broadcasts from a tower at the beach, it very well could be heard 100-200 miles away if there are no other stations occupying its frequency being received from elsewhere.

Such a blockbuster event occurred on July 14, 2005. Assisting in the study of a duct covering a large majority of the lower half of Lake Michigan was John Rieger in South Milwaukee, Wisconsin. Chris Kadlec was stationed across the lake at Kruse Park in Muskegon, where 107 stations were logged on a full dial. Fog that afternoon was thick and accumulating to heights of 50 or more feet along the shore. It is possible that the fog, created by an extreme temperature difference, covered a large portion of Lake Michigan that afternoon and assisted in creating a duct that would essentially make a regional local listening area. Low-powered stations over 150 miles away were received and with a high degree of accuracy, Rieger and Kadlec both logged the same stations despite being 85 miles apart. The difference in air and water temperature on the Michigan side was between 35 and 40 degrees at any given time that day. While air temperatures were in the low 90s, water temperatures hovered in the upper 50s, a rare condition for the middle of July caused by upwelling of water from below the lake surface and a nearby awkward weather pattern with easterly winds created by Tropical Depression Dennis. The dewpoint was in the mid-60s and as determined by the dense fog over the lake, air temperatures over the lake’s surface were also in the mid-60s, a near 30-degree difference from a few hundred feet inland and a few hundred feet above the lake’s surface where radio-friendly conditions quickly deteriorated.

Intense openings in the Great Lakes aren’t limited only to Lake Michigan. Other large lakes such as Lake Ontario and Lake Erie, both longer lakes that more commonly receive east-west tropo, also participate in long distance catches. On Lake Ontario, the easternmost of the five lakes, long-distance catches can be an almost daily event. The 175-mile stretch between Hamilton and Kingston, Ontario is often easily traversed given the absence of any interference. The Buffalo market is commonly heard in the Kingston area and Rochester is heard even more often in Ontario. Ontario DXer Saul Chernos, who is known to tune in stations at the Scarborough Bluffs east of Toronto and at his home 45 miles inland, says that conditions over Lake Ontario can vary greatly during any given period of time. “Syracuse can be strong one minute, and then it can be Watertown, Utica, Rochester, or Buffalo,” he says. “It can shift around. Watertown can get really strong and Rochester can drop out substantially, or Rochester can get really strong and come in along with, or perhaps without, Watertown.” Syracuse isn’t all that uncommon on the shores of Ontario and Ottawa can be readily heard on many days in Rochester, 185 miles to the southwest.

Michael Procop, 10 miles inland from Lake Erie near Cleveland, reports lake conditions are to blame for the constant reception of Detroit stations 110 miles to the northwest, both on FM and on TV. Grand Rapids, Michigan, in excess of 200 miles, can also be heard and seen interfering with nearby stations on an occasional basis. Although London and Chatham, Ontario to the north of Cleveland are very common, Buffalo, 175 miles to the northeast, and its adjoining Toronto and Hamilton markets are rarely heard, if ever. Detroit, 200 miles due west of Dunkirk, New York, on Lake Erie’s southeast shore, can be heard often while driving along the New York Thruway. Assisted by higher elevation to the north in Ontario, Cleveland and Erie stations are rather commonly heard in London and Brantford, Ontario and as far west as Port Huron, Michigan.

Despite the parallel nature of Lake Erie and Lake Ontario, cross-lake reception between the two is a very rare occurrence. The Niagara Escarpment, the most prominent topographical feature in Southern Ontario, separates the two watersheds preventing any low-lying lake tropo from escaping either lake. In addition, there is a 325-foot elevation difference between the two water bodies that only upper-level long-haul tropospheric ducts could easily pass over. There is a drop of more than 400 feet at the Niagara Escarpment in Grimsby. While this would no doubt block any and all stations originating from across Lake Ontario, it would be possible, although maybe unlikely, for stations from across Lake Erie to fall into Lake Ontario ducts.

Although Lake Huron and Lake Superior are also known to produce cross-lake signals, both lakes are larger and far less densely populated with stations. This fact hasn’t stopped either Paul LaFreniere of Grand Marais, Minnesota or Jacob Norlund of the Duluth area from receiving stations across Lake Superior. Elevations in Minnesota’s North Shore region can top 1,600 feet within miles of the lake, while exceeding 2,000 feet within ten miles of the shore north of Grand Marais, 70 miles southwest of Thunder Bay, Ontario. LaFreniere reported that he receives many stations from Michigan’s Upper Peninsula, including those from Iron Mountain (93.1 WIMK), Marquette (94.1 WUPK, 95.7 WHWL, and 103.3 WFXD), and Escanaba’s 106.3 WMXG, among many others, some of which are also heard along the shores of Lake Michigan. Also reported as being received often was Newberry’s 50-killowatt 93.9 WNBY 265 miles to the southeast and Sault Ste. Marie’s 100-kilowatt 99.5 WYSS, received occasionally at a distance of 300 miles. In addition to the more powerful stations, LaFreniere reported often hearing translator stations with as little power as 5 or 10 watts based along the shore 90-100 miles to the south. However, Norlund’s location near Duluth yielded far fewer favourable results due to the poor location of Duluth in relation to the remainder of the Lake Superior shore. Evidence attempting to determine the possibility of cross-lake tropo extending across both Lake Michigan and Superior was inconclusive, but is considered unlikely.

The sun’s effect on cross-lake ducts is especially apparent during the strongest of the lake openings. It is widely known that the sun affects both E-Skip and tropospheric reception, but the sun paired with its reflection off a large body of water is even more important. As noticed during afternoon and evening DX sessions along Grand Haven City Beach throughout the summer of 2006, the position of the sun in the sky can, but not always, determine the direction from which the strongest reception originates. It was often noted that while the strongest stations originated from Green Bay, Milwaukee, and Chicago as the sun was at its highest points throughout the day, reception after dusk turned largely south toward the South Bend market in a higher elevation parallel to the lake’s shore. This was noticed on many evenings as the sun set around 9:30. It can be assumed that if the shore of the lake north of Grand Haven, which extends toward the northwest, had not been blocking straight-line water paths for signals, this phenomenon would have repeated to the north as well with stations from Escanaba and Marquette. However, these locations do not have nearly as many stations and any instance of that would largely have gone unnoticed. On some nights though, July 23rd, 2006 being a great example, one half of the FM dial was heard from one location while the other half was from a different location specifically at sunset. On this day, most signals before the sunset were from the south end of the lake near Chicago. Stations after sunset were from the north end of the lake near Green Bay. As the sun set into the lake, the bottom half of the dial came in from Green Bay while the top half of the dial came in from Chicago. Minute by minute after sunset stations could be heard changing from the bottom to the top of the dial, the most common fashion in which the dial changes from one locale to an opposing locale on an opposite end of the lake. This is almost similar to the maximum usable frequency (MUF) experienced as E-Skip reception climbs up the dial through VHF and into the FM band.

Lake breezes and their effect on ducts and reception

If it seems like radio stations are being blown onto land by the breezes along the beach, you might not be imagining it. The lake breeze can be a very important aspect to a lake inversion event and reception patterns can change drastically as the breeze starts up or dies down. Since 2003, a noticeable lake breeze from the northwest was noted on about eighty percent of days that had an intense cross-lake radio opening. On some of those days, more than 100 different stations were received, while on a select few days, in excess of 150 stations were recorded. These lake breezes on numerous days clear skies as far as 35 miles inland, just east of Fremont, extending cross-lake signals within the affected area. Just as the lake breeze gradually thins out and becomes weaker as it reaches further inland, the quality of station reception also becomes weaker as one travels inland away from the lake.

Due to the temperature differences fueled by the often cooler water beside warmer land, lake breezes can form during the daytime in the spring and summer seasons along the lakeshore. The higher pressure (the cooler air) over the cooler water is forced inland toward the lower pressure (the warmer air) as the atmosphere seeks to equalize pressure, thus creating the breeze. With stable air masses, especially on a clear day, this difference in air pressure can set up a constant lake breeze that essentially becomes a tropospheric duct in itself, which as a dome of cool air, provides a duct of lower attenuation of signals where signals are bent down instead of up toward the sky and are thus travelling parallel to the lake surface. The most common scenario is southeast or northeast winds that abruptly shift to northwest winds sometimes in a matter of mere minutes, most often – but not always – in the mid to late-morning hours, shifting back to a land breeze soon after sunset. The ducts exist in part because of the wind, yet it appears, given the radio data in comparison with the weather data, that the ducts open shortly before the lake breeze starts up and on days of weaker lake breezes may close immediately as the lake breeze moves into a land breeze, while on days of intense openings may take several hours to close.

When conditions change as the sun sets, the lake breeze collapses as the land becomes cooler and the water becomes warmer and the lake breeze becomes a land breeze – although weaker, a breeze blowing from land toward the water. With this event, the ducts that had been open all day due to the onshore breeze suddenly diminish as the breeze blowing from the land onto the water blocks or weakens any ducts formerly open. It is believed possible that this is the main cause for Chicago reception changing quickly into South Bend reception after sunset. In addition, the formation of a land breeze is likely to create a region of free-flowing reception over the water close to the shore – technically, a land air mass with a western boundary over the lake. The one market that is best equipped to utilize such an open area of reception is South Bend. With a straight-line path that meets Lake Michigan, South Bend signals, more often blocked during a cross-lake opening, freely travel over open water near the shoreline before running aground in Grand Haven as the shoreline gradually juts into the lake. Increased reception of Green Bay signals have also been noted during land breezes. The aforementioned event of Chicago stations turning to Green Bay stations at sunset is a likely example of this, as Green Bay stations can often be heard well in the Ludington area, which easily places them in a land breeze duct.

Collapsing lake breezes can have other effects as well. Storms that come in over the lake and quickly cool the air over land can create downdrafts as they advance eastward. These downdrafts are capable of pushing lake breezes further inland and extending any lake inversion ducts that currently exist over Lake Michigan. Poor weather conditions are no reason to sit in the house thinking the dial is quiet. It has been noted during numerous occasions that Green Bay stations are often present in Fremont during heavy rainstorms, usually an oddity in most locations where storms greatly hamper station reception. Most commonly heard during rainstorms is Green Bay’s 96-kilowatt powerhouse 101.1 WIXX-FM, which is otherwise heard slightly less during the average clear summer day. WIXX is 121 miles to the northwest and broadcasts from a tower at an elevation of 899 feet from a transmitter at 1,827 feet above sea level, among the higher stations in close proximity to the lake. On a clear day, WIXX’s signal usually extends to the Michigan shore. Fremont, 25 miles inland, is the furthest point inland before moraines start to dot the landscape and is the highest non-moraine elevation which is most often the furthest inland extent of a lake breeze.

Lake breezes can be physically noted on many days by the presence of clear skies over the water with partly cloudy skies over land. It is not uncommon to see a line of cumulus clouds separating the boundary between a lake breeze and land-based conditions. The cumulus clouds often develop in lines near the shore along the distinct boundary, called the lake breeze front. On some days, a lake breeze front that has pushed up to 35 miles inland can develop thunderstorms, especially on days of strong lake breezes. On June 29, 2005, a day of strong cross-lake radio reception, a lake breeze front formed a weak landspout tornado just east of Grant.

In the winter, long after the lake inversion season has ended, lake-effect snow squalls affect the area that the summer lake breeze previously affected. In a scenario in which a lake breeze extends only to Holton, 15 miles inland, winter snow squalls will follow this same pattern thus extending only to Holton unless otherwise affected by stronger than average winds. In the summer, many radio stations begin their cross-lake coverage area at this same location on an average day. Many Green Bay stations studied between the summers of 2002 and 2004 were noticed to start coming in around Holton, abruptly falling from the sky just as abruptly as clear inland skies turn to lake-effect snow squalls in the winter.

Determining land-based vs. water-based tropo

Determining which mode of tropospheric ducting you are hearing can be almost as difficult as trying to identify an NPR station via E-Skip at the bottom of the dial. This is especially true when DXing many miles inland away from the lake where you cannot compare between signals on the beach and signals further inland. Sometimes it isn’t even worth the effort to determine which you are receiving. Instead, just enjoy the fact that you are indeed receiving something. But when studying the very idea of cross-lake tropo as compared to general tropo, it’s worth looking at indicating factors.

In the absence of a lake breeze, nighttime openings are often general tropo or enhancement, that is, tropo that is not solely produced by Lake Michigan. This isn’t always the case as there are many summer nights when conditions over the lake continue and sometimes increase reception along the beach yet are non-existent a half-mile inland. On many nights, there is constant reception, although often not as strong as in the day and more often than not, from Green Bay or South Bend as opposed to Milwaukee and Chicago. During the day, determining which mode you are receiving can be slightly more complex. Is the water temperature abnormally cold as compared to an abnormally high air temperature (or the reverse during the off-season)? Is there a northwest wind off the lake? More than likely you’re listening to signals that are assisted only by lake conditions. Are the skies clear with atmospheric high pressure overhead? It could very well be longer-range tropo well beyond the effects of the lake. On a day when conditions are stable throughout, tropo ducts may easily stretch from Iowa straight to Michigan without interference. More often than not though, conditions over the cooler water break any existing over-land ducts as they hit the lake. Stations may even fall into another lower-level duct and effectively cross Lake Michigan unhampered.

The unexplained distant locals

A set of cross-lake stations nearby to the western shore of Lake Michigan was the focus of a 2004 study. These few stations, three in Wisconsin and one in Indiana, would often come in on summer days with local-like quality and on many occasions could be heard on neighbouring frequencies as well almost as if they were 10 or 20 miles away. In fact, three of the stations – 95.1 WIIL-FM near Kenosha, 100.7 WKKV-FM near Racine, and 99.1 WMYX-FM near Milwaukee – were sometimes even stronger than local stations. While WKKV and WMYX have towers broadcasting about 11 miles from the lake, WIIL’s signal originates at a tower 4 miles from the lake. The study, which aimed to determine why these distant stations carried such a pattern, found that two of the three – WMYX and WKKV – broadcasted from towers 800 feet above sea level and transmitters within a 30-foot vertical height of each other, despite being 10 miles apart. WMYX transmitted from 1,237 feet above sea level at a distance of 112 miles from Fremont while WKKV transmitted from 1,266 feet above sea level at a distance of 115 miles from Fremont. The strongest of the three, often being heard when conditions are dead on both sides of the lake, is WIIL-FM. The station, even common in the winter and loud and clear on many nights when enhancement originates solely from inland Michigan, was found to increase significantly in strength at 750 feet and higher, a few miles west of the city of Fremont. On days during which the station cannot be heard near the lake, the station rises from the static near this location. It was found that WIIL-FM, unlike the other two dominant stations, originates from a tower at 686 feet and transmits from 1,070 feet above sea level 115 miles southwest of Fremont. All three stations broadcast at an ERP of 50 kilowatts. The three stations were also found to abruptly appear over the final moraine on state highway M-37 between Sparta and Kent City, about 25 miles inland. Glenn Hauser, editor of the “DX Listening Digest” and host of the “World of Radio” program, says in response to the distant locals that “probably because of prevailing tropospheric conditions, ducts habitually form at a certain elevation or range of elevations.”

Two other studied stations of interest originated at the north and south ends of Lake Michigan. Power 92 WPWX-FM, an urban station serving the Chicago market and licensed to Hammond, Indiana, where its tower stands along the state line, can be heard up to 150 miles on either side of the lake and on select days much further. Its partner in long-distance broadcasting, 46-kilowatt 99.7 The Bay WZBY-FM (formerly urban station Wild 99.7 WLYD-FM), has been heard virtually on all sides of Lake Michigan from Milwaukee and Chicago to Grand Rapids and as far south and inland as Kalamazoo. Listeners in South Bend, 225 miles from the station’s tower near Sturgeon Bay, Wisconsin, have reported occasional reception and the southern shore of Lake Michigan in towns like Portage, home of Indiana DXer Roger Winsor, have also reported hearing the station at a much higher frequency. Because the Door Peninsula, home to Sturgeon Bay, extends 45 miles out into Lake Michigan as compared to the average western coastline of the lake, the station can extend in all directions as well as east toward the Mackinac Bridge, territory less common to widespread lake inversion openings due to less straight-line access to distant stations.

Communication interference via lake inversion

As anyone who often comes to the beach with their cellphone or their radio knows, the beach can be a pretty hostile environment for those accustomed to a clear signal. On days of strong lake inversion openings, an opening can also mean a closing.

Stations from Wisconsin, Illinois, and Indiana that arrive on the beach with power equal to what one would hear five or ten miles from the originating radio tower simply blow away any local stations more than ten miles from the beach. On numerous days, even local station 100.1 WVIB-FM 18 miles to the northeast will vanish under booming Port Washington, Wisconsin religious station, WPJP-FM Relevant Radio, 92 miles to the northwest. Most if not all Grand Rapids stations often disappear, replaced with Chicago and Green Bay area stations, some as weak as a few thousand watts. On rare days, all locals will disappear into oblivion. Milwaukee’s [former] classical station WFMR-FM 106.9 on some days was able to completely take out WMUS-FM in Muskegon, a strong 50-kilowatt local station just 14 miles to the northeast. Grand Rapids’ local 300-kilowatt powerhouse 93.7 WBCT has been held hostage more than once by WEKZ-FM of Monroe, Wisconsin, 178 miles to the west. Although this was likely accompanied by land-based tropo, the power of the lake inversion and lake breeze that assisted it was intense enough to wipe one of the nation’s most powerful stations clear off the dial on the beach.

Cellular phones are greatly affected by any lake inversion opening. It is locally known that if you visit the beach carrying a phone with a certain service provider, you can almost always watch your phone switch to Central Time Zone (observed on the opposite side of the lake) as you near the beach. On occasion, your entire local service may be interrupted and all outgoing calls will be sent from towers 80-150 miles away on the other side of the lake. This gives a new definition to “roaming” when you’re being charged extra to use a distant tower when your local tower is just a mere one mile inland. Chicagoland tourists who spend time in Grand Haven often complain to the workers at the Bil-Mar Restaurant, a popular local beachside eatery at the foot of a gradually-sloping 103-foot bluff, that their cellular service does not work. Instances of complaints predictably rose drastically on days of strong lake inversion events that included Chicago stations especially. Instead of receiving service from across the lake, all service was denied. Although cellphone reception patterns cannot be officially determined as phones do not specify the exact tower they have connected with as does a radio station, it is believed that signals from Milwaukee towers at a distance of about 85 miles are near enough to easily cross the lake.

Interference via intense lake inversion events can be compared to a strong wind blowing off the lake on a hot summer day. The strongest effects of a lake breeze can be experienced within about a half-mile of the shore, sometimes further if the signals travel up the river, which they are known to do. The breeze can easily extend 35 miles inland where communications will likely face interference, less inland as compared to the shore. Beyond that, east of the lake breeze front, all is often calm and normal.

The effects of lake inversion especially in Grand Haven are captured by the close proximity of the bluff and the road, Harbor Drive, which runs between the beach and bluffs, a rarity in many tourism-based West Michigan beach towns. Travelling up the western side of the bluff to Five Mile Hill in Grand Haven, 125 feet above the water, one can easily hear different stations coming in and out, sometimes switching back and forth between stations at a rapid pace, a result of different ducts at different elevations and stations reflecting off the duct walls. Upon reaching the top of the bluff, where there is no land to interfere with the signals, local inland stations can often be heard as they normally would. Any remaining cross-lake signals that are included in higher-level surface ducts can be heard as well.

Conclusion

After a few years of flipping through the dial, a great deal has been learned. Months of endless curiosity led to years of never-ending questioning. Hours spent by the beach sitting in a hot car logging stations have been good times, good music, and some pretty good and exciting tropo catches. In the end, the natural tropospheric duct we call Lake Michigan is better understood yet still ever so unpredictable. Over the course of a single summer, over 7,000 entries were added to the logs. The summer log consisted of 67 individual days spanning just over three months. The average entry rate was 100 per day and over 100 individual stations were recorded on some days. The data and the associated report took a full year to organize. The concluding summer of the study in Grand Haven, Michigan was without any doubt an overwhelming success.