Transcript Air and Weather

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
► 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
Earth is moving to the
east)
► Doldrums
Wind Systems
– windless zone at the equator
► Trade Winds – 15o North or South of the
equator blow to the southwest (NH)/northwest
(SH)
► Prevailing Westerlies – 30o and 60o 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
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► Air
Weather Patterns
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