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Thermoclines: also in the air?
When I took scuba diving as a class my freshman year of college, I learned about thermoclines. They are the point in the water where the temperature suddenly drops/rises (depending if you're going down or back up). Seeing as air and water are both fluids from a technical standpoint, do thermoclines exist in the air? If so, what factors come into play at what altitude it's at?
Re: Thermoclines: also in the air?
The International Standard Atmosphere (ISA) assumes a constant decrease in temperature of 2 degrees per 1000 ft, up to the tropospause (at 36.000 ft), at which point the temperature remains at a constant -56 degrees for the next few kilometers.
The way I understand it (correct me if I'm wrong), thermoclines are a result of the water near the surface being heated and mixed by the sun and wind. As such, radiation fog could be described as a thermocline layer. The heat in the ground radiates out into space, cooling the very lowest air-mass, saturating the air and causing fog to form.
The way I understand it (correct me if I'm wrong), thermoclines are a result of the water near the surface being heated and mixed by the sun and wind. As such, radiation fog could be described as a thermocline layer. The heat in the ground radiates out into space, cooling the very lowest air-mass, saturating the air and causing fog to form.
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- einsteinboricua
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Re: Thermoclines: also in the air?
TWA772LR wrote:do thermoclines exist in the air? If so, what factors come into play at what altitude it's at?
Thermoclines are the whole reason we have weather in the first place.
Air (the atmosphere) is a fluid so it can also experience a thermocline. The major thermoclines you should know are the ones for the different atmospheric layers:
Notice how temperature fluctuates with altitude increase.
Now, let's focus on the troposphere, which is where all of the weather happens. Notice how as you go up, temperature goes down. Air temperature behaves differently: cold air sinks while warm air rises. If your top layer is warm air and the bottom layer is cold air, no mixing should happen (that's why at night there's usually not a lot of weather going on...cold air remains on the ground with no rising motion while warm air remains aloft or will cool and sink). However, if you invert the scenario (warmer air near the ground and cooler air with altitude), warm air will want to rise. If you add daytime heating, you have the ingredients set for a weather event. How strong the event will be will depend on the lapse rate: the rate at which air is cooled as you go up. That also behaves as a thermocline.
So yeah...the factors that will affect it are the density of the air, the temperature, and its content (is it humid or is it dry?).
Re: Thermoclines: also in the air?
einsteinboricua wrote:If your top layer is warm air and the bottom layer is cold air, no mixing should happen (that's why at night there's usually not a lot of weather going on...cold air remains on the ground with no rising motion while warm air remains aloft or will cool and sink).
Depends on what you consider "weather", I suppose.
Cold air near the ground below warmer air (also known as a temperature inversion) often leads to fog on or near the ground.