Download How does precipitation form?

HOW DOES
PRECIPITATION FORM?
Chapter 5, Lesson 2
Cloud Formation
• Clouds form and release precipitation in
the form of snow, sleet, and hail.
• The Sun warms the Earth’s surface.
• The air gets warm too.
• Warm air rises in to the sky.
Cloud Formation
• It cools up high in the atmosphere, and gets
heavy.
• So it sinks back down to the ground.
• This is called convection.
• A convection current is a loop of moving air
or liquid that transfers energy.
Cloud Formation
• Warm air carries more water vapor than
cool air.
• The water vapor forms tiny drops of water,
that remain in the air and form clouds.
Forms of Precipitation
• The kinds of precipitation that fall from
clouds depends on what it is like inside
the clouds, and what it is like in the air.
• Drops of liquid water are rain.
• Rain forms when tiny cloud drops
combine.
• A large number of these drops must
combine to be heavy enough to fall to
the ground.
Forms of Precipitation
• Sleet begins as tiny drops of rain.
• The raindrops fall through a layer of air
that is colder than water’s freezing
point.
• This causes the rain to freeze.
Forms of Precipitation
• Snow falls as flakes and small balls of ice.
• Sometimes the temperature in a cloud is
cold enough for water vapor to turn to ice
crystals.
• Cold temperatures make light, fluffy flakes.
• Warmer temperatures produce heavy, wet
flakes of snow.