Ch. 24.1: Layers of the Atmosphere

Troposphere • 0-12km• Weather & Clouds• Greatest air

pressure & density (Gravity pulls air to surface)

• Temp. DECREASES with altitude

WHY?

Stratosphere • 12 km – 50 km,• Temperatures

WARM from -57C to 0C.

• Upper strat. is warmer than lower b/c of OZONE LAYER (This is unexpected)

OZONE LAYER • Ozone absorbs UV that can be

harmful to organisms.

• UV Thermal Energy which warms strato.

• • OZONE HOLE = Thinning of ozone

layer) – Where: over poles– Cause: chemicals, CFCs

(Chloroflourocarbons), used as coolants in refrigeration and aerosols, get into atmosphere and break apart ozone molecule … allowing more UV in.

Mesosphere • 50-80 km,• Temps decrease as

altitude increases• Top of Meso. is -

90 C• Very thin air –

moving VERY FAST. Windy (320 km/hr).

• This burns up meteoroids

Thermosphere• OUTER MOST LAYER• 80 km – outer space• TEMP INCREASES w/

Alititude. ( - 90 C to more than 1000 C)

• B/C gas molecules in thermo. Absorb solar radiation – move fast – high temps

Ionosphere• Part of THERMOSPHERE• Region of charged

particles (ions) that overlaps the lower thermoshere.

• Molecules absorb solar energy and b/cm (+) charged or IONS.

• Aurora – Charged particles are attracted to E’s mag. Poles – collide w/ ions & glow

Challenge

Air exerts 14.7 pounds of pressure on each square in of Earth’s surface.

• Air Pressure = 14.7 lbs/in^2• How much would YOU have to weigh to exert

the same pressure on Earth?