Cold, Winter Nights

January 25, 2018

As Michiganders, we know cold, winter nights. We also know that on cloudy nights, the clouds seem to form a blanket and it does not get as cold as the clear, cloudless nights when the stars shine bright against the black, cold, abyss of space. In reality, the clouds do form a blanket. This insulation process that the clouds are demonstrating is a phenomena called the greenhouse effect.

When the greenhouse effect gets mentioned, the first, and possibly only, example people think of is climate change. Climate change is being driven by excessive carbon dioxide (CO2) in the atmosphere that traps heat as it tries to radiate back into space. However, it is not the only gas that behaves in such a way; water vapor (H2O) is also a greenhouse gas.
In both situations, (the water vapor in the cloud cover and increasing carbon dioxide that is causing climate change), heat is trapped as it tries to radiate away from the Earth. We must remember that it gets cold at night because heat is escaping into space, not the cold of space sinking onto the Earth.

It is the water vapor within the cloud cover that makes a noticeable effect. In areas around Michigan, morning temperature reports will have various low temperatures based on cloud cover. In fact, water vapor has the greatest greenhouse, heat-trapping effect, when compared to any of the other greenhouse gases.

The amount of water vapor in the atmosphere has been stable of millenniums. (Although it is on the rise with the increase in ocean temperatures.) Therefore, it is of little or no concern in reference towards climate change. The water vapor has always been there and will always be there.

Although, carbon dioxide may trap less heat when compared to water, the amount of carbon dioxide is rising. Unlike the water cycle where the same water molecules pass from sky to sea and back again, the carbon within carbon dioxide is new to the atmosphere. It had been locked up within the fossil fuels buried underground for millenniums. As fossil fuels are burned, the carbon within the fuel combines with oxygen and is transformed into vast amounts of new carbon dioxide. With the increase in carbon dioxide, there is an increase in the heat trapped by the greenhouse effect.

As Michigander, we do have first-hand experience with warming effect of water vapor on a clouding night. The water vapor does form a blanket to keep the outdoor temperatures warm. Carbon dioxide does this exact process as well, and although blankets feel good on cold, winter nights; we do not need them on a hot, summer day.

Andrew J. Frisch
Science and Mathematics Teacher,
Farwell High School

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