Download • The water cycle is the movement of • How does water vapor enter

Water in the Atmosphere
Major Steps of the Water Cycle:
• The water cycle is the movement of
water between the atmosphere and
Earth’s surface.
• How does water vapor enter the air?
Evaporation/Transpiration
• Explain evaporation : The process by
which water molecules in liquid water
escape into the air as water vapor.
• The water vapor is now in the air and
forms clouds by condensation.
• How does water return to bodies of
water?
When water droplets become too large to
remain in the cloud, they fall to Earth as
precipitation. Water flows back to a body
of water – runoff.
Other terms to know:
• Transpiration - When plants release water
into the atmosphere.
• Runoff - precipitation water that runs
over land on its way back to a body of
water.
Details:
Evaporation (pg 54):
• An increase in energy (from solar
radiation), causes water molecules to
move faster, fast enough to change
matter from a liquid to a gas.
• Water (liquid) changes into water
vapor (gas).
• Warm air above the surface of the
Earth has molecules that are more
spread out (less dense), which means
there is room for more water vapor.
• This water vapor then rises with the
rising warm air during convection.
Condensation:
• The rising air during convection starts to
cool.
• Because the air molecules lose energy,
they start to slow down, move closer
together, and the air becomes more
dense.
• When the air cools, and becomes more
dense, there is no more room for water
vapor.
• The air is full or saturated and the water
vapor is forced out and condenses or
turns back into a liquid.
• The temperature at which condensation
begins is called the
dew point.
• What is needed for water vapor to
condense? (pg 57)
Tiny particles must be present so
the water has a surface to
condense on.
• When water molecules condense on
particle, CLOUDS are formed.
Precipitation (pg 62):
• Eventually, clouds become very heavy, due to
all those clinging water drops.
• Precipitation is any form of water that falls
from clouds and reaches Earth’s surface.
• Describe the five types of precipitation:
1.Rain:
• Liquid water drops
• Most common kind of
precipitation.
2. Sleet:
• Rain that passes through a layer
of below freezing air on its way to
the ground. Water drops freeze in
ice.
3. Freezing Rain:
• Rain drops that freeze when they
touch a cold surface.
4. Snow:
• Water vapor converted directly
into ice crystals. Snowflakes
have many different shapes and
patterns.
5. Hail:
• Forms inside cumulonimbus
clouds (thunderstorm clouds).
• Round pieces of ice formed when
frozen drops get blown back up
into the cloud combine, become
heavy and fall to the ground.