|Friends of the Lakeshore Nature Preserve||
Wind Research at the Tent colony
My first trip from the Tent Colony pier to the Second Point Bar was by boat as a 1960 first-year graduate student in the Department of Meteorology (now Atmospheric and Oceanic Science). Today, when I walk the Lakeshore Nature Preserve path through the Tent Colony Woods, memories of my first research project come back. Memories of wind, waves, ice, and friction, and the Gallistel Cottage.
The Tent Colony pier and the Gallistel Cottage are gone, and, to be clear, the Second Point Bar was not an early campus watering hole, but a sub-surface shallowing of the bottom of Lake Mendota. The “Bar,” about 400m north of the tip of Second Point (now Frautschi Point) is only 4m below the lake surface with relatively steep falls to the west, north, and east, known as a good place to catch fish. There I caught not fish, but the “bug” of scientific curiosity.
In 1959, the Department of Meteorology conducted climate studies by erecting an instrumented steel tower anchored to the Bar, laying submarine cables to transmit data from the tower to the recently vacated Gallistel Cottage, and installing remote monitoring instruments, IBM data processing equipment, a small electronics and instrumentation shop, and storage facilities in the cottage. In January 1960, as a research assistant with Professor Lettau I helped complete the tower instrumentation and participated in experiments to answer the question: How much is wind slowed by friction near the earth’s surface? The nature of this question is apparent to anyone walking to Picnic Point when a strong wind blows from the north. The trees slow the wind until you reach the narrow section of treeless beach, and then you feel its full force. Likewise, a canoeist on the placid leeside shore of University Bay rounds Picnic Point and immediately copes with wind and wave.
But the science question was: Can we measure the precise frictional effect of lake water and ice, just as we measure wind speed or temperature or weight? It matters! The slowing of wind near the surface affects the flight habits of insects, the spacing of wind turbines, the pollution of cities, and the evaporation rate from vegetation.
The Bar offered the advantage of measuring one parameter at a time, unusual for outdoor earth science. The lake is a uniform surface stretching far to the west, north, and east, and when the wind is almost steady the lake becomes a lab for studying friction. Using a vertical array of precision anemometers I first measured the friction effect over bare ice. Then I placed bushel baskets on the ice —first far apart, then close together, then piled on top of one another. As I decreased the spacing between the baskets or increased their height, I measured how much the wind slowed. In the following winter, with other students I repeated the experiments using discarded Christmas trees, creating a moveable forest on the lake. We calculated exactly how the height, spacing and size of these obstacles slowed the wind, and found that we could change the rate at which wind energy was lost by friction by a factor of 10. This information now helps scientists calculate the “friction” of natural objects such as grass, cornfields, forests, or cities, and is used worldwide to estimate the effects of wind.
I then measured the interaction between wind and waves—light wind and tiny capillary waves, strong winds and large 1–2 foot waves. The higher the waves, the larger the frictional loss of wind energy to water.
The period of intense climate-related experimentation off Second Point lasted from 1959 to 1969. Then the Second Point Bar tower, the submarine cables, and the Gallistel Cottage were removed. Now, walking the Tent Colony path and looking out at the Second Point Bar reminds me of our pioneering research and it excites me when I hear of the many research projects now underway on the Lakeshore Nature Preserve grounds.
In one project, Professor Ankur Desai and colleagues are measuring the exchange of carbon dioxide between the lake and air using instruments installed atop the UW Safety Tower at Picnic Point. Research in this “lake ecosystem” will contribute to studies of carbon cycling worldwide—in forest, grassland, tundra, and ocean environments—both present and future.
The Meteorology research station seen from the lake side in 1959/60. Far left Gallistel house, a pier, the meteorology lab shack, and on the far right a smaller observation shack along the water line. A larger tent structure above. Later the Meteorology department used the Gallistel House for equipment storage. Photo Kutzbach