11.2 Properties of the 11.2 Properties of the atmosphereatmosphere

TemperatureTemperature• A measure of the A measure of the average kinetic average kinetic

energy energy of the particles in a material.of the particles in a material.• Can be measured in:Can be measured in:

– ° F, ° C, or Kelvin (K)° F, ° C, or Kelvin (K)

Air Pressure Air Pressure --• is the force exerted by the air, is the force exerted by the air,

whether compressed or unconfinedwhether compressed or unconfined

Air pressure and AltitudeAir pressure and AltitudeAir pressure of the atmosphere Air pressure of the atmosphere

decreasesdecreases as altitude as altitude increasesincreases..

DensityDensityThe measurement of the amount of The measurement of the amount of

matter that occupies a given space.matter that occupies a given space.

Air Density and AltitudeAir Density and AltitudeIf you’re at a If you’re at a higher altitudehigher altitude, the , the

thinner the air the thinner the air the lower the air lower the air densitydensity..

Pressure, temperature, and Pressure, temperature, and density density - Warmer air has - Warmer air has less pressure less pressure than than

cooler aircooler air- Air with a - Air with a higher density higher density has a has a higherhigher

pressurepressure- Warmer air is - Warmer air is less dense less dense than cooler than cooler

airair

Temperature inversion Temperature inversion

Temperature inversion-Temperature inversion- a increase in a increase in temperature with an height in an temperature with an height in an atmosphere layer.atmosphere layer.

Causes- rapid cooling occurs preventing Causes- rapid cooling occurs preventing the radiation of thermal energy to the the radiation of thermal energy to the lower layers of the atmosphere.lower layers of the atmosphere.

Effects- fogs or low level cloudsEffects- fogs or low level clouds

WindWind

WindWind- the - the movementmovement of airof airWind occurs because the warm air has Wind occurs because the warm air has

less pressure/less dense than cold air.less pressure/less dense than cold air.Therefore wind will always move from Therefore wind will always move from

cold to warm.cold to warm.(on a hot day when you walk into a cold (on a hot day when you walk into a cold

building with A/C – the cold air rushes building with A/C – the cold air rushes OUT when you open the door!)OUT when you open the door!)

QUIZ QUESTIONS!!!QUIZ QUESTIONS!!!

Q. What causes wind and Q. What causes wind and air differences?air differences?

A. Unequal heating in A. Unequal heating in cooling of different cooling of different

regions of Earth surfaceregions of Earth surface

Q. When does Q. When does temperature inversion temperature inversion occur?occur?

Warmer air is on top of Warmer air is on top of cooler air .cooler air .