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hot air rises and cold air sinks question?
We all know that there is a theory whereby hot air rises and cold air sinks right,then why would we feel cooler at the top of the mountain instead of hotter (since theres a theory"hot air rises, cold air sinks"??
8 Answers
- 1 decade agoFavorite Answer
As you move upward the atmosphere cools. This happens at a rate of about 3 degrees F per thousand feet. This makes sense when you think of the temperature differential between the Earth's surface and that of free space. The atmosphere also becomes less dense and therefore can hold less heat.
As warm air rises it is depressurized and looses heat which in turn slows down it rate of rise. You can actually see this in the shape of developing thunderstorms they frequently develop an anvil shaped head where the formerly warmer and water laden air has stopped climbing. Relatively speaking this is low level stuff and happens between 30,000 and 60,000 feet. These effects are a big part of our weather patterns.
- Anonymous1 decade ago
All of your answers so far are wrong.
Hot air does indeed rise. Why does this happen? Well, its because the pressure in the atmosphere falls as you gain altitude (because there is less atmosphere over your head pushing down); the hot air is less dense than that around it, so this pressure gradient gives rise to a net force pushing up on the hot air.
But as the hot air rises it experiences that lower pressure. And so it expands. From the gas laws you will know that if a constant mass of gas expands without any energy input it cools down. Utlimately it will cool down enough that it no longer rises.
What this means is that air is naturally cooler the higher you go.
The atmosphere is in a stable equilibrium when the change in temperature as you rise is exactly what is necessary to stop pocket of hot air rising. This is called the adiabatic lapse rate, and it is about 0.65 C per 100m. So if you go up a 1000m mountain the top is 6.5C cooler than the bottom. If you go up to 10,000m in a plane it is 65 C cooler (the outside of a plane is typically around -50C).
- Brian LLv 71 decade ago
Hot air rising is not a theory - it's a fact. That's why hot air balloons work.
There are several reasons you feel colder at the top of a mountain. Here are the two biggest ones, in no particular order:
1) More wind. Wind sucks heat out of you because more air is moving past you, and that air absorbs heat from your body. There's more wind because there's nothing up there to block it.
2) Low air pressure. Low-pressure air holds heat less well than air at ground level. That's why air can sink back to the ground again - it loses its heat, and it sinks, and it heats up, and it rises, and on and on.
- DavidK93Lv 71 decade ago
Hot air rises because it is less dense than cold air. But it only rises until it contracts and loses its heat, so it's no longer hot by the time it approaches high altitudes. Meanwhile, at very high elevations, the atmosphere is much thinner than it is at the surface of the Earth, so it has much less heat content as well.
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- 1 decade ago
There is less air higher up therefore less atmosphere. Also you're subject to higher winds and there's still snow left over from winter a lot of times.
- Amy FLv 51 decade ago
I think it's because the atmosphere is thinner up there. The atmosphere holds heat near the Earth like a blanket, so the thinner it is, the more heat can escape.
- ?Lv 71 decade ago
Because there is less atmosphere up there..the higher you go the colder it gets.
(Thermals (rising heat currents) generally take place in the lower regions (the atmosphere's lower regions that is).
- Anonymous1 decade ago
alitude,climate and air pressure goes into play here. expically climate. if there is no hot air to rise when its cold then u wouldnt feel hot.