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Lesson 25
How do snow, sleet, and hail
form?
Have you ever packed a
snowball or made a snowman?
You cannot shape rain because it
is liquid, and as we know, liquids
cannot have a shape of their
own.
Snow is different, it is a solid,
and solids have a shape of their
own.
We can change the shape of
snow after it hits the ground.
Snow is one kind of solid
precipitation.
There are other kinds;
sleet
hail
Snow, sleet and hail form in
different ways.
Snow
Water vapor condenses to form
clouds. If the temperature
around the clouds if above
freezing, the vapor changes to
liquid droplets.
If, however, the temperature
around the clouds is below
freezing, the vapor turns to tiny
snow crystals.
The tiny snow crystals grow and
grow.
When they become heavy
enough, they fall to earth.
Hail forms during
thunderstorms.
Strong air currents keep
raindrops moving in the air for a
long time.
As they move, they pass through
many cold and warm layers of
air.
In the cold air, raindrops freeze.
They change to ice beads.
In the warm air, water builds up
around the beads.
Then the water freezes when
they pass through another cold
layer.
This happens over and over
again. Each time the icy beads
become bigger.
Finally, they become hailstones,
are too heavy for the air currents
to carry them, and they fall to
earth.