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SCIENCE ~ CHAPTER 8
WEATHER
Miss Nelson
SECTION 2
Precipitation
ANTICIPATORY SET
What types of precipitation have you
personally experienced?
How are they different from one another?
STANDARDS
S 6.4.e –
Students know differences in pressure, heat, air
movement, and humidity result in change in
weather
THE BIG IDEA
What are the common types
of precipitation?
KEY TERMS
 Precipitation – any form of water that
falls from the clouds and reaches
Earth’s surface
PRECIPITATION
 Water evaporates from every water surface on Earth
and from living things
 Eventually, this water returns to the surface as
precipitation
 Not all clouds produce precipitation
 For precipitation to occur, cloud droplets or ice
crystals must grow heavy enough to fall through the
air
T YPES OF PRECIPITATION
Common types of precipitation
include:
Rain
Hail
Snow
Sleet
Freezing rain
RAIN
Most common kind of precipitation
Droplets are called rain if they are at
least .5 millimeters in diameter
Smaller = drizzle
Smaller than that = mist
Drizzle/mist usually fall from stratus clouds
HAIL
Round pellets of ice larger than 5 millimeters
in diameter are called hailstones
Hail forms only inside cumulonimbus clouds
during thunderstorms
View the diagram on page 308 of your textbook
SNOW
 Often, water vapor in a cloud is converted directly
into ice crystals
 Called snowflakes
 Have an endless number of different shapes and patterns
 All have six sides and branches
 When snow falls through humid air that is close to
freezing, the snowflakes tend to join together into
larger clumps
SLEET
When raindrops fall through a layer of air
that is below 0 degrees Celsius (the
freezing point of water) they freeze into
solid particles of ice
Ice particles smaller than 5 millimeters
in diameter are called sleet
FREEZING RAIN
Sometimes raindrops falling through
cold air near the ground do not freeze in
the air
Instead, they freeze when they touch a
cold surface
Called freezing rain
T YPES OF PRECIPITATION
Read Types of Precipitation on pages 308-309
of your textbook
CHECK FOR UNDERSTANDING
What are the five common types of
precipitation?
What is the difference between freezing
rain and sleet?
CHECK FOR UNDERSTANDING
What are the five common types of precipitation?
The five common types of precipitation are rain,
sleet, freezing rain, hail, and snow.
What is the difference between freezing rain and
sleet?
The difference between freezing rain and sleet is
that freezing rain is water that freezes when it
touches a cold surface, where as sleet is water
that freezes in the air.
GUIDED PRACTICE
How does hail form?
Hail forms start as small pellets of ice in
cumulonimbus clouds. They grow larger as they are
repeatedly tossed up and down, until they become so
heavy that they fall to the ground.
A thunderstorm produces precipitation in the form of
ice particles that are about 6 millimeters in
diameter. What type of precipitation is this?
This type of precipitation is hail.
INDEPENDENT PRACTICE
Complete Weather 8-2 Independent
Practice