You’re watching FreeSchool! Any time you look up into the sky, you may
see clouds – but no two clouds look alike, and some look very different from each other.
So, what makes clouds? And why do some clouds look thin and wispy, while others look big
and fluffy? Clouds are formed by water vapor in the atmosphere
that condenses into very small water droplets or ice crystals and then gathers together. When water on the earth evaporates, it turns
into invisible vapor that rises until it reaches colder air high in the sky. In these colder
temperatures, the vapor condenses, or changes back into a liquid. Eventually, the water
droplets will fall back to earth as rain, snow, or
ice. This is known as the water cycle. There is always at least some water vapor
in the air. Clouds only form when the atmosphere cannot hold any more vapor. Since warm air
can hold more water vapor than cool air, clouds are often formed when the temperature cools. Although they may look light and fluffy, clouds
are actually very heavy. A single cloud may weigh as much as several million tons. They
do not fall because warm air currents push up against the tiny droplets, and individual
droplets are not heavy enough to overcome the resistance of the air below them until
they join together into much larger drops. There are five basic types of clouds: cirrus,
stratus, stratocumulus, cumulus, and cumulonimbus. Cirrus clouds are high and thin. Because the
air is so cold at high altitudes, these clouds are made of ice crystals instead of water
droplets. Cirrus clouds are sometimes called “mares’ tails” because they are shaped something
like the tail of a horse. The appearance of cirrus clouds often means a day of fair weather. Stratus clouds are shaped like flat sheets.
They may occur at low, middle, or high altitudes. When stratus clouds layer thickly, they may
produce light rain or snow. Stratocumulus clouds make rolls or ripples,
and can occur at low, middle, or high altitudes. Cumulus clouds are puffy and small when they
first form, but they may grow into much taller cloud formations. When lit by the sun, cumulus
clouds are bright white and are often seen on days of good weather. Cumulonimbus clouds are thunderclouds. Heavy
and dense, they are very large and similar to cumulus clouds. They may produce lightning,
rain, hail, and tornadoes. Different types of clouds can indicate different
kinds of weather, but aside from that, identifying clouds is fun! Next time you are outside,
look up! And see if you can identify the clouds where you are.