Ch.5 Atmospheric Pressure and Winds

The Nature of Atmospheric Pressure and Winds

Gas molecules are continuous in motion

-collide with each other and surfaces in contact with

-force of collisions against surface is pressure of gas

How are areas of high and low atmospheric pressure produced?

-differential heating

What determines the direction in which wind blows?

-pressure and

What are the global patterns of wind and pressure, and how do they form?
What are monsoons and how do they form?

Atmospheric Pressure-is force exerted by weight of gas molecules on unit of Earth’s surface or other body.

-sea level pressure is greatest than decrease with increasing altitude

-exerted on every surface, equally in all directions

Factors influence atmospheric pressure

-pressure, temperature, and density of gas are all related

P=pRT

P=increases if density p or temperature T increases, R is constant

Density and Pressure Relationships

-density is mass of matter in a unit of volume

-gas density varies greatly by location

-pressure is proportional to gas’s density, with greater density, high pressure

Temerpature and Pressure Relationships

-Increase in temperature produces increase in pressure, if other conditions are constant

-when particles are warm, they move faster, collide more frequently and exert more force as pressure

-decrease in temperature results in decrease in pressure

-pressure depends on more than just temperature and density

Dynamic Influences on Air Pressure

along with air density and air temperature, the movement of air impacts surface pressure

-air pressure may be influenced by the vertical movement of air, as well as convergence and divergence

Dynamic Highs-are areas of strongly decsending air

Thermal Highs-have very cold surface conditions

Dynamic Lows-are areas of strongly rising air

Thermal lows-have very warm surface conditions

Mapping Pressure with Isobars