Linking to Climate and Weather
After helping your students to understand the nature and composition
of clouds, you can make a smooth transition to a discussion of precipitation.
A thorough understanding of the physical conditions favoring various forms
of precipitation is probably beyond the scope of the elementary science
curriculum, but what they investigate here will provide some building
blocks for this to happen at a later stage.
Here are some questions for your students to consider (with explanations
in italics):
- Ask the students what would happen inside a cloud as droplets became
larger and larger. (Soon, they would be too heavy to remain suspended
in air. Slowly, at first, the droplets begin to fall toward the Earth.
When larger droplets catch up with smaller droplets, they combine and
begin to fall even faster. Soon large drops form and fall to the ground
as rain.)
- Ask your students how snow, sleet and hail might form. (If raindrops
fall through very cold air near the Earth's surface they may freeze.
Then we get little grains of ice pellets or sleet. Snowflakes, however,
form inside the clouds themselves when conditions are right for crystals
to form. Hailstones travel downward through a cloud and pick up a coating
of water that freezes on the surface, before being carried upward by
strong drafts within the cloud. The hailstone will fall again, picking
up another layer of ice, and be carried back up the cloud again, growing
a bit each time, until it finally is too heavy for the draft to carry
it upward. At that time, it falls to the ground.)
After developing a concept of clouds, you can show students pictures
of all of the various types of clouds in the sky. Learning to observe
these clouds and relating them to specific weather conditions is an interesting
extension of this investigation. There are many excellent books and tables
displaying all of the various cloud varieties. Many of these resources
are available on the Web, for example the National
Oceanic and Atmospheric Administration (NOAA).
You may also wish to have the students add information about cloud type
and cloud cover to their daily weather journals.
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