Transcript water in the atmosphere - Fort Thomas Independent Schools

WATER IN THE
ATMOSPHERE
WATER CYCLE
 Water is always moving between the
atmosphere and Earth’s surface.
 This movement is known as the water cycle.
 3 major processes of the water cycle
– Evaporation
– Condensation
– Precipitation
Evaporation
 When liquid water
changes into a gas.
 This is also known as
water vapor.
 Water vapor usually
comes from a body of
water, such as,
oceans, ponds, lakes,
stream, or even
puddles.
Humidity
 The amount of
water vapor in the
air.
 It can vary from
place to place.
 Air is saturated
when the
evaporation is equal
to the condensation.
Relative humidity
 It compares the
amount of water
vapor in the air with
the maximum
amount that it can
hold.
 50% RH is about ½
of the amount of
water need for
saturation.
Condensation
 Water vapor cools and
condenses into liquid
water.
 These condensed
water droplets clump
together around tiny
dust particles to form
clouds.
Cumulus Clouds
 Means “heap or mass”
 Forms less than 2 km above the ground and
can extend 18km up.
 Indicates fair weather
 Fluffy rounded piles
 Cumulonimbus – often produce
thunderstorms.
STRATUS CLOUDS
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Means “spread out”
Form flat layers
Cover all or most of the sky
As they thicken they may produce drizzle,
rain, or snow
Fog
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A cloud that rests on the ground or over a body of water.
Forms when surface is colder than the air above it.
It clears as the ground is heated by the sun.
CIRRUS
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High clouds
Wispy and feathery
Made mostly of ice crystals
Cirrocumulus: looks like a row of cotton balls
Often indicate a storm is on the way.
Precipitation
 Water droplets that get
heavy enough to fall to
the Earth’s surface.
 Forms of precipitation
include: rain, snow,
sleet, and hail.
 Most water molecules
spend about 10 days
in the atmosphere.
 Rain most common
form of precipitation.
 Snow is water vapor that
freezes directly into ice
crystals. The ice crystals
will clump together and
form snowflakes.
 Sleet raindrops that
freezes as they fall through
the atmosphere.
 Hail starts as an ice pellet,
as it falls through the
atmosphere is melts and
refreezes forming a
hailstone.
PRECIP. CONTINUE
 Rain needs to be at
least .5mm in diameter
 Freezing rain is rain
that freezes when it
hits the ground not in
the air.
 Precipitation
ALWAYS comes from
clouds, but not ALL
clouds produce
precipitation.