If warm air rises why is it cold on the top of a mountain?

Answer 1

There are some number of factors involved here:

Firstly, it is true that warm air rises, but as it gradually rises, it becomes thinner and expands, which possesses a cooling effect. On the high mountain ranges, the surrounding atmospheric air is very thin: so that there is also not much surrounding air to hold the heat in when the sun does warm the mountain, and much of the warming effect escapes.

Secondly, mountain tops are further from the thermal heat at the earth's centre.

Thirdly, is the angle of incidence over which the sun's rays meet the earth's surface itself. An overhead sun, for instance, meets a flat earth surface very directly - an almost perpendicular 'attack', you might say. A 1 metre stretch of sun affects about 1 metre of earth's surface from directly above. However, if the sun meets the mountain side at [say] an angle of depression of 60 degrees, then the same amount of sun will cover 2 metres of ground; so its overall warming effect will be greatly lessened.

Answer 2

Well the short answer is that we live in a sea of air, and lower altitudes have higher air pressure than higher altitudes do just as deeper ocean depths have greater pressures than more shallow ones. Temperatures rise with pressure. The end. ... Well, not quite, since air is largely transparent to heat radiation, the earth warms the air from the bottom and the air loses heat into space. The end.

And now the long answer: Air is made up of molecules: little bits of 'stuff' that have mass ('heaviness') and are always moving about at some speed. Like billiard balls, when one slams into another one, it gives some of its energy to the other one and loses some of its own. In air, all these molecules are moving around randomly; some molecules are moving away from a denser group (where they are bunched closer together) and as they leave, they take energy away from the group, and some are moving toward the denser area bring their energy to the group. Heat is the average kinetic energy of this group. Add a very large amount of heat to a very small area of air very quickly, and you get an explosion: the air will move away from the area very rapidly. Now run it in reverse, compress air into a smaller space, and it will heat up. (Here is where I leave it to interested persons to look up Newton's laws of motion and the "gas laws".)

(Since gases are compressible, this effect is much more dramatic for gases than for liquids, like water.)

The air is largely transparent to heat energy and doesn't easily heat up by absorbing it (though it does to an extent). This largely leaves the earth to heat up the air from the bottom.

And, as the earth's gravity pulls the air molecules toward the earth, the ones closest to the earth's surface have not only their own weight pulling them down, but are being pushed down by the weight of all the billions of molecules above them. With all that weight comes a lot of the downward energy of all the molecules above them- add to it the heat energy from the sun-heated ground; these molecules gain more energy and lose less energy, and so they are "hotter". As you go higher and higher, the number of molecules above any given population of molecules at a given altitude grows to be less and less. And since these guys are all moving around randomly, a greater number are more likely to move away from the denser area because they aren't being pushed down by as many of their neighbors; and as they leave, they take their energy ("heat") away with them. And that is why it's cooler at higher altitudes.

Answer 3

Air is colder at higher altitudes because it is less dense i.e. less molecules of air 'living' in an area. Therefore, there is less heat transfer between the molecules. I suppose, you COULD think of it as less friction between the molecules - might not be too correct though.

Answer 4

Primarily because the atmospheric pressure is decreasing (the higher you go, the less atmosphere is above you), and temperature goes down as pressure goes down. It's also true that the sun heats the earth's surface and generally not the atmosphere, but this has little to do with the temperature dropping as you go up.

Answer 5

Your about to leave Earth's regular temperature. In other words, at the surface of Earth, it's actually more warmer down there. But once you get higher, it starts to get less warmer and starts to get more colder. The higher you go, the colder it gets.

Answer 6

Yes, warm air rises but it also expands and cools in the process. It also loses its ability to hold heat.