The Various Forms of Precipitation
Weather affects our lives daily, so it would enrich us to
learn more about it. While there are only a few basic types of weather,
people in the mountains in Vail, Colorado experience the snow
differently than those living in New York City, and those living on the
coastline experience rain a different way than people living on the
Rain is the form of precipitation seen most frequently in the
world, and densely populated areas with much urban development and
vehicle traffic receive a majority of the rainfall. The reason for this
is because raindrops are formed around particles that were released
into the air by vehicle exhausts. Although many people who grew up
watching cartoons believe that raindrops are shaped like a teardrop,
small ones are actually round and they become hamburger bun shaped and
then more doughnut shaped as they get larger.
A Network of volunteers measuring the rainfall across the
Little balls of ice raining down from the sky during a storm
are known as hail. Hail is formed when a thunderhead cloud with
powerful, upward air movement moves raindrops around inside of it. As a
raindrop begins to fall, it is caught by the updraft in the cloud and
taken to the upper levels where it freezes. It then becomes too heavy
to remain at the top so it falls to the bottom of the cloud where the
updraft catches it again and the cycle starts all over again.
Hailstones can be little pellets or a few inches in diameter, and many
have interesting stripes caused when a new layer of ice was added each
time it went to the top of the cloud.
Hail.org is all about hail and includes news, maps and
- WAAESD This link is to the paper
on managing and utilizing precipitation observations
Freezing Rain differs from hail in that hail is little balls
of ice and freezing rain is supercooled water droplets. This occurs
when rain falls in an area where the temperature of surfaces on the
ground is below freezing. When the droplets hit objects on the ground,
everything becomes glazed with ice.
- HPS discusses freezing rain in
conjunction with health
Sleet is fine rain droplets that have frozen in the cloud.
When they hit the ground they do not melt but rather bounce off of the
surface they hit. Sleet is almost always spherical, and it only forms
when the weather conditions are perfect to produce it. When a cloud
forms snow but the snow has to travel through a warm layer of
atmosphere to get to the ground, it melts. When it reaches the layer
above the ground which is still below freezing, the melted snow
refreezes into the perfect little ball known as sleet.
- WW2010 The University of
Illinois offers a comprehensive weather site here.
Snow is water in crystal form that falls to the ground and
blows around if it is very cold or packs down if there is a cycle of
freezing and thawing. It is formed when water particles are frozen and
remain in a supersaturated cloud to continue growing. Snow can cause
major commuting problems but it is the only type of precipitation that
can be used for recreation.
NSIDC is the National Snow and Ice Data Center
- Snow and a variety of its causes
- Thinkquest offers a variety of
activities to teach about snow
- Storm 2K is a forum dedicated to
weather related issues
NOAA Is the National Oceanic and Atmospheric Administration
with in depth weather coverage
Weather.org offers some insight into how weather is