Category Archives: Meteorology

When can it get really hot in southern Wisconsin?

Our cold early April seems to have finally given way to a surging spring. Now that we have seemingly emerged from winter, with reasonable confidence that we will not go back, it is interesting to consider when truly summerlike weather might first appear in southern Wisconsin.

One measure of summer here is a daytime high temperature at or above 90 degrees. In Madison, there have been only three April days when the high temperature was that warm. Continue reading

Category: Climate, Meteorology, Seasons

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What connection does UW-Madison have with the National Weather Service?

Last week, the director of the National Weather Service (NWS), Louis W. Uccellini, visited his alma mater as the Department of Atmospheric and Oceanic Sciences inaugural Distinguished Alumni Award winner.

Uccellini presented the story of the intellectual and professional journey that led him to the leadership of this extraordinarily important government agency. Continue reading

Category: Meteorology

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What is the effect of snow cover on weather and climate?

Even as a few flurries filled the sky on Friday, it is clearly almost the end of the snow season for southern Wisconsin.

While few mourn its passing by this time every year, it is interesting to consider the profound effect that snow cover has on the weather and climate of the middle latitudes. Continue reading

Category: Meteorology, Seasons

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How do you measure weather far above the ground?

Meteorologists monitor the atmosphere above the Earth’s surface by using a radio-equipped weather instrument package carried aloft by a helium-filled “weather balloon.” These instrument packages are called radiosondes (“sonde” is French for “probe”).

Radiosondes measure vertical profiles of air temperature, relative humidity and pressure from the ground all the way up to about 19 miles above. At low air pressures in the stratosphere, the balloon expands so much that it explodes and the radiosonde drifts back to the ground underneath a small parachute. Continue reading

Category: Meteorology

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Why are there different types of precipitation?

When particles fall from clouds and reach the surface as precipitation, they do so primarily as rain, snow, freezing rain or sleet.

The main difference between these different types of precipitation is the temperature variations between the cloud base and the ground. Last week, Madison experienced all four of these precipitation types. Continue reading

Category: Meteorology, Seasons

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