If cold air is heavier than hot air and sinks to the ground then how come high mountains have snow?

Question

If cold air is heavier than hot air and sinks to the ground then how come high mountains have snow?

Answer 1

Cold air is heavier than hot air *at the same pressure*. But when going up, pressure reduces. If you were to take air from atop a mountain and adiabatically compress it to sea level pressure, it would actually be hotter than sea level air.

Answer 2

Not all the cold air sinks.If warm air raises over a place due to buoyancy,almost equal amount of cold air sinks in the nearby high pressure area and proceeds towards(as wind) the low pressure area to replace it.So,most of the cold air at higher altitudes remains there only.

Answer 3

This is a very interesting question, KL!

First, the temperature of the air sinks on an average of 0.65 C per 100 meter of altitude. This is because the sun heats the ground and hot air on the surface rises and cools down by adiabatic effect (this is the same principle that happens in your refrigerator!)

The process continues to the top of the troposphere, at about 12 km of altitude where it reaches about - 50 C.

But, as you say, cold air sinks and it means that, when there is no wind in a mountainous country like Norway (where I live), during the night the cold air falls from the mountain tops into the valleys creating a wind. In places like Greenland, that wind can even reach a storm force that has been known to have destroyed villages!

But when the sun heats up the ground during the day, the process reverses and the valleys become warmer again.

Answer 4

Don't listen to PicturePerfect.  As heat is added to air its volume increases with the increased molucular activity.  Density = mass/volume.  If the top number stays the same & the bottom increases, the density becomes less (hot air is less dense than cold air).

BUT, as the hot air rises and disapates further apart, it loses some of the kenetic energy that made it warm.  it begins to cool again.  This is why water vapor becomes clouds which in turn becomes rain falling back to the ground.  When it reaches Earth again, the water can get warm and evaporate into vapor again.  

The higher the elevation, the thinner the air is (ask any sports star that VISITS Mile high Denver, Colorado!)  Mountain tops have higher elevations and thus less warmth.

Enjoy!

Answer 5

Less atmospheric pressure, in other words the air is thinner.  As I'm sure you know, if you compress a gas (including air), it gets hotter.  That's because compression squeezes the molecules closer together and they since they are already running and jumping around like John Travolta disco dancing, they run into each other even more, raising the temp.

On a mountain top, the thinner air spreads the molecules out, less head banging occures, thus a cooler temperature.  

Chinook winds are warming winds that occur in mountainous areas.  These winds rush down the mountainside to lower elevations and as the atmospheric pressure increases at the lower elevation, the air heats up.

Answer 6

Because the higher you get (in the sky) the colder it is so on the top of the mountain, its really cold, so thats why it snows.

higher altitude=colder

Answer 7

You've got it the wrong way around!

Hot air is denser. Cold air is lighter.