Download Observe Precipitation

OBSERVE PRECIPITATION
Video Summary
Water that falls from the sky is called
precipitation. As one aspect of weather,
precipitation such as rain or snow can
affect your daily life. However, it is also
a vital step in the water cycle, returning
water from the atmosphere back to
Earth’s surface. In this video segment
produced for Teachers’ Domain, observe www.teachersdomain.org/resources/ess05/sci/ess/watcyc/precipitation
three different types of precipitation—rain, hail, and snow.
Topics Covered:
– Earth and Space Science:
Water Cycle, Weather, and Climate
Recommended for Grades K-5
Media Type: QuickTime Video
Video Length: 0m 59s
Permitted use: Download, Share, Remix
This media resource can be used only for non-commercial, educational purposes.
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Discussion Questions
 What substance makes up rain, hail, and snow?
 How are rain, hail, and snow alike? How are they different?
 Have you experienced rain? Hail? Snow? How would you describe each
form of precipitation to someone who had never experienced it?
 What is the source of the water that makes rain, hail, and snow?
 What happens to the water from rain, hail, or snow after the precipitation
falls to the ground?
Background Essay
The water cycle—the continuous exchange of water between Earth’s surface and
atmosphere—is Earth’s natural mechanism for recycling water. Liquid water on Earth’s
surface evaporates to become water vapor in the atmosphere; the water vapor produces
clouds and precipitation; and the precipitation returns water to the surface.
Clouds are collections of billions of water droplets or ice crystals. When a mass of air is
saturated with water and the temperature remains above 0°C (32°F), the water vapor
Observe Precipitation
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© 2007 WGBH Educational Foundation. All rights reserved.
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condenses around particles in the air to form tiny droplets of water. If the temperature is
below 0°C (32°F), water vapor is directly deposited as ice crystals. When the water
droplets or ice crystals become too heavy to remain suspended in the atmosphere, they
fall to Earth’s surface as precipitation.
The two main forms of precipitation—rain and snow—can appear in many variations,
including freezing rain, sleet, and hail. The type of precipitation that falls depends on the
temperature of the air—both where the precipitation forms and through which it falls.
When the air temperature is above 0°C (32°F), the precipitation falls as rain because
the water stays in liquid form. When the air temperature is below 0°C (32°F),
snow—crystalline flakes of frozen water—falls. Snowflakes take time to melt, so they can
survive passing through a thin layer of air above 0°C (32°F), and snow can fall even
when the air at ground level is warm. On the other hand, if rain—or snow that passed
through a large enough warm layer that it melted—has to pass through a layer of freezing
air near the ground, it may turn into sleet or freezing rain. Sleet is made up of drops of
water that freeze near the ground, and freezing rain is made up of supercooled drops
that freeze upon impact with surfaces below 0°C (32°F).
Hail—lumps of ice that can become as large as baseballs—forms in severe thunderstorm
clouds that contain both rain and snow. As a snowflake falls through the cloud, water
freezes around it and the pellet grows larger in size. Strong updrafts in the cloud then
toss the frozen lump back up towards the top of the storm. As it falls through the cloud
again, more layers of ice may be added. This may happen again and again, and it
continues until the hailstone becomes too massive to be supported by the updraft and falls
to the ground.
To learn more about the phases of water, check out Water Phases.
To learn more about the water cycle, check out Water Cycle Animation.
To learn more about clouds, check out Cloud Types.
Lesson Plans Using This Resource:
– Cycling Water Through the Environment
– What’s the Weather?
Curricular Standards Correlations:
NSES, Project 2061, MCREL, and state standards correlations available at
www.teachersdomain.org. (Free registration required for your specific state standards correlated to this resource.)
Source: Produced for Teacher’s Domain
Observe Precipitation
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© 2007 WGBH Educational Foundation. All rights reserved.
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Materials used courtesy of:
Rain on rooftop footage from WGBH Educational Foundation. All other stock footage (of rain, hail, and
snow) courtesy of NOAA (National Oceanic & Atmospheric Administration).
Collection developed and produced for Teachers’ Domain by:
Collection funded by:
”Teachers‘ Domain is proud to be a Pathways portal to the National Science Digital Library.”
Observe Precipitation
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© 2007 WGBH Educational Foundation. All rights reserved.
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