Question

The high pressure areas are formed by molecules cooling and getting closer together, being dense they drop and leave space into which air flows in causing high pressure. And as wind flows from high pressure to low pressure, SHOULDN'T WIND ALWAYS BE COLD?​

Answer 1

Answer:

. Air exerts a force on surface of objects.

A. Air pressure is force per unit area.

B. It is cumulative force of a multitude of molecules.

C. Pressure depends on:

1. Mass of molecules

2. Pull of gravity

3. Kinetic energy of molecules

II. Normally a pressure balance between air and objects.

III. Pressure decreases with height.

A. Max air density occurs at surface.

B. Air becomes "thinner" with height.

C. Affects on humans:

1. Dizziness, headaches, shortness of breath in mountains

2. "Ear-popping"

IV. Horizontal variations in pressure

A. Altitude dependent, but this is corrected to sea-level

B. After corrections, still are variations because:

1. Different air masses

2. Air is compressible

3. Air circulation

C. Air mass - huge volume of air that is relatively uniform in temperature and water vapor.

1. Pressure increases with warmer temperatures (in closed container)

2. But atmosphere has no walls, so heated air expands, becomes less dense. Thus, net result is that pressure actually decreases when heated.

a. Greater activity of the heated molecules increases the spacing between neighboring molecules and thus reduces air density. The decreasing air density then lowers the pressure exerted by the air. Warm air is thus lighter (less dense) than cold air and consequently exerts less pressure.

3. Moist air is less dense than dry air!!

4. Sinking air increases pressure at surface, and ascent decreases pressure at surface.

5. In addition air pressure changes caused by variations of temperature and water vapor content, air pressure can also be influenced by the circulation pattern of air.

V. There is pressure variations at all time scales.

A. Long-term

B. Diurnal (daily)

VI. Circulations - definitions

A. Divergence - net outlfow of air from a region or area.

a. If more air diverges at the surface than descends from aloft, then the air density and air pressure decrease.

b. Conversely, If less air diverges at the surface than descends from aloft, then the air density and air pressure increases.