Air and Weather Chapter 9 and 10

Atmosphere ► 5 layers: ► 1. Troposphere – area closest to the ground, 75%of the gases, dust, ice and liquid water-Weather, Clouds, and smog occur here ► 2. Stratosphere – Ozone layer ► 3. Mesosphere – ► 4. Thermosphere – contains the ionosphere where electrical charged particles are (get AM radio at night when sun goes down, particles quit jumping) ► 5. Exosphere – upper most portion portion

► Energy Transfer occurs by: ► Radiation – electromagnetic waves, no contact but still feel it, moves from object with a higher temperature to one with a lower temperature ► Conduction – direct contact, fast moving molecules to slow moving molecules ► Convection – density differences, air is warmed, the air molecules move apart which increases the volume of air which reduces its density thus the air raises and causes a circular movement of air called a convection current

Movement of Air ► Earth’s surface is curved rather than flat, air equator is heated more than any other place on Earth ► Coriolis Effect – caused by Earth’s rotation, air masses moving south in the Northern Hemisphere are turned westward (because westward (because Earth is moving to the Earth is moving to the east) east)

Wind Systems ► Doldrums – windless zone at the equator ► Trade Winds – 15 o North or South of the equator blow to the southwest (NH)/northwest (SH) ► Prevailing Westerlies – 30 o and 60 o North and South winds blow in the opposite direction as the trade winds SW to NE in NH and in SH NW to SE ► Polar Easterlies – NE to SW near the North Pole and from the SE to the NW in the SH ► Jet Streams – winds near top of troposphere ► Sea and Land Breezes – convection current where land meets the sea (sea/day – land/night)

Factors of Weather ► Humidity – amount of water vapor in the air ► (cooler air, slower, condenses – rains ► Hot air, faster, air holds more moisture ► Relative humidity – amount of water vapor in air as a percentage of amount it can hold  Saturated air – 100% relative humidity  Dew Point – temperature at which it condenses ► Clouds formed when the humid air is cooled to its dew point and condenses ► Fog- is a stratus cloud close to the ground ► Precipitation – occurs when water droplets reach.2 mm

Weather Patterns ► Air mass – large body of air that has the same properties as the surface over which it develops ► Fronts – boundary between 2 air masses as they collide ► Warm Front – warm air mass slides under cold air mass (less dense) High cirrus clouds, ► Cold Front – cold air invades cold, cumulus clouds and rain ► Stationary Front – pressure differences and it doesn’t move lights winds and rains ► Occluded Front – 2 cool air masses forces warm air up, heavy precipitation and wind ► Precipitation from warm air being cooled cooled