Explain why pressure decreases but temperature varies as altitude increases?

Question

Explain why pressure decreases but temperature varies as altitude increases?

Answer 1

Even though the pressure does decrease with increasing altitude, the temperature is not a solely dependent on the air pressure.  There are ways that temperatures can vary with altitude, such as when a cold arctic airmass slides under a warmer airmass.  This creates an inversion at the top of the cold and dense airmass, with the warmer air lying above it.  Subsidence from upper level high pressure areas causes the air to heat and become drier, and that can create another type of inversion, trapping a layer of relatively cooler air below.  Water vapor that condenses into clouds releases heat, which changes the temperature profile of the atmosphere as well.

Answer 2

Pressure and temperature are proportional in a system of constant volume .

The equation is PV = nRT

n and R are "constants' persay  so if you take them out you have

PV = T, and so on V = T/P

The link below shows you a good example of what happens when a column of air is compressed, or cooled/warmed.

As the altitude increaes, the pressure and temperature BOTH decrease...  because fewer air molecules exist the higher you go up.  As a result, the air molecules are spaced out more and cannot absorb/emit the sun's radiation as much.  The pressure also drops as a result because in order to keep the volume the same, you must have both decrease proportionally.  

For example, temp is 300K and pres is 1000 mb.  If the temp drops to 280K to keep volume the same the pres must now be about 933 mb.

Please note that of course the answer would be different due to the constants n and R and volume in air columns DOES change in reality.

This is just an example, but temperature can vary as mentioned above due to more complicated weather systems with differing volumes.

Answer 3

Ever gone swimming in a lake?  As you go down into the water the pressure increases and your ears feel the increased pressure.  Same as when you go up into the atmosphere, less air on top of you - less pressure.  The temperature goes down because there is less air to hold the heat as you go up into the air and there is nothing to heat it higher in the atmosphere.

Answer 4

The pressure part I think I can answer. Pressure (in this case) is dependent on gravity. The further you get from the center of the earth the less gravity (pressure) there is. Imagine pressure as the weight of air above you. Also think of swimming in a pool. The deeper you get the more pressure increases.

Tempurature is indepedent of altitude.