Transcript Water in the Atmosphere

Water in the Atmosphere
The Water Cycle
HUMIDITY…
 A measure of the amount of water vapor in
the air
 Relative Humidity: % of water vapor in the
air compared to the maximum amount the
air can hold
 Warm air can hold more water vapor than
cool air
 Evaporation slows down when the relative
humidity is high
How Clouds Form…
 When water vapor in the air becomes liquid
water or ice crystals
 Condensation: molecules of water vapor
become liquid water
 Dew Point: temperature at which
condensation begins
Cumulus Clouds…
 Look like fluffy,
rounded piles of cotton
 Cumulus means
“heap” or “mass”
 Indicate fair weather
 Cumulonimbus clouds
are towering with flat
tops that produce
thunderstorms
 Nimbus means “rain”
Stratus Clouds…
 Form in flat layers
 Strato means “spread
out”
 Cover all or most of
sky
 Nimbostratus clouds
may produce drizzle,
rain, or snow
Cirrus Clouds…
 Wispy, feathery clouds
 Form only at high
levels – above 6 km
 Made mostly of ice
crystals
 Cirrocumulus clouds
look like rows of cotton
balls and indicate that
a storm is on its way
Clouds based on Height…
 Alto- (means high): clouds that form between 2 & 6 km
above Earth’s surface.
– Altocumulus
– Altostratus
 Fog: clouds that form at or near the ground
– Forms when the ground cools at night after a warm,
humid day. The ground cools the air just above it to the
air’s dew point. The next morning’s sun “burns” the fog
off as its water droplets evaporate