02 Clouds

There are several types of clouds that appear in the sky at various times of year. These different kinds of clouds can result in weather that brings rain or snow, or may simply stop the Sun from shining brightly. Clouds are made from tiny water droplets or ice crystals.

There are three basic forms of clouds. Stratus clouds form in a blanket-like layer. Cumulus clouds are puffy clouds that appear to rise up from a flat bottom. Finally, cirrus clouds form at very high altitudes out of ice crystals, and have a wispy, feather-like shape. The term “nimbus” is added to the name of the cloud if it brings rain or snow to an area.

The height of a cloud allows it to be grouped into a family. The families are: low clouds, middle clouds, high clouds, clouds that develop upwards, and clouds that develop vertically. Thunderstorms come from cumulonimbus clouds that develop upward.

Another type of cloud is fog. This kind of cloud develops at ground level. Any form of water particles that fall from the atmosphere and reach the ground is called precipitation. This happens when the water droplets or ice crystals in the cloud join together and become heavy enough to fall. This is how precipitation happens. It depends on the temperature in the cloud and in the air whether the precipitation will fall as rain or snow.

Heavy precipitation often comes from large cumulus clouds. On the other hand, long lasting precipitation comes from stratus clouds. Vertically-developed clouds hold the most precipitation. They are very turbulent, and often cause heavy downpours or even large amounts of snow. This is called a “cloudburst”.

Word List

puffy : soft and pillowy

vertically : up and down

precipitation : droplets that fall to Earth in the form of rain, snow, hail, etc.

turbulent : changing very quickly

downpour : very heavy rain

You Practice

I. Answer the following questions.

1) What are the three basic types of clouds?

2) What are the various cloud families?

3) How is fog different from other kinds of cloud?

4) Why does snow sometimes happen instead of rain?

5) Why is it a good idea to bring an umbrella outside if there are vertically-formed clouds in the sky?

II. Fill in the blanks—Complete the following sentences with words from the reading.

1) Clouds are made from very small water d _ _ _ _ _ _ _.

2) Cumulonimbus clouds develop u _ _ _ _ _.

3) The lowest kind of cloud is f _ _.

4) Very heavy rain is called a d _ _ _ _ _ _ _.

5) Cumulus clouds look p _ _ _ _.

III. True / False / Not Given—Write T if the sentence is true, F if it is not true, or NG if there is no information about this sentence.

____ 1) Precipitation happens when water droplets join together and become heavy enough to fall.

____ 2) Cirrus clouds develop close to the ground.

____ 3) Nimbus is added to a name if there is thunder.

____ 4) Downpours usually happen when there are wispy clouds.

____ 5) Stratus clouds are formed out of ice crystals.