Clouds and Precipitation
A cloud is a collection of moisture in the air. Clouds consist of millions of tiny water droplets or ice crystals. Water is found in the air as an invisible gas called water vapor. This vapor is formed when the sun heats water in lakes, rivers, and oceans. The heat makes the water evaporate, turning it into vapor, and rising into the air. Humidity is the amount of water vapor in the air. There are three things that must occur for a cloud to form: relative humidity must be close to one hundred percent, tiny bits of matter, such as dust, must be present, and something must happen to cool the air. The types of clouds that form depend on how cold the air is and how much water is in the air. There are many different types of clouds, and several different environmental reasons why clouds form. These different clouds are named based on their size, shape, and height in the sky. Clouds indicate, or show, the current weather conditions, and help meteorologists predict near and future weather. Clouds are often associated with precipitation, like rain, sleet, snow, or hail.
The air contains millions of microscopic dust particles. When moist air rises or evaporates, due to heat, it expands. This evaporated water is called water vapor. When water vapor in the air is cooled, it condenses. It turns back into a liquid and attaches to dust particles in the air. These very small water droplets group together to form clouds. The temperature change that causes cloud formation is referred to as the dew point. If the cloud temperature falls below freezing, the tiny water droplets will freeze and form ice crystals; therefore, clouds consist of either tiny water droplets or ice crystals. There are three main types of clouds, which are named based on their shape and height in sky. These three main cloud types are cirrus, cumulus, and stratus. These different clouds can appear in the sky in different combinations at the same time. Cirrus clouds are high-level clouds that are usually found above 20,000 feet. These clouds are made of ice crystals and have a light, feathery look in the sky. Cumulus clouds are found at different heights in the sky. These clouds are the rounder, puffier clouds with flat bases. Often, cumulus clouds are seen on dry, sunny afternoons. Stratus clouds are distinctive in that they form a layer, or sheet, of clouds across the sky. These clouds are found at lower levels, usually below 1,650 feet. Stratus clouds often produce precipitation such as light rain. Cirrus clouds are made of ice crystals and found very high in the sky. They usually have a wispy, feathery look. Cumulus clouds are round, puffy clouds. They are found at different levels in the sky. These are usually the clouds that we see on dry, sunny days. Stratus clouds are lower in the sky. They are very unique, because they often made a sheet, or layer of clouds in the sky. Different clouds indicate the weather conditions. For example, stratus clouds are often a sign of precipitation. They are usually the clouds we see on rainy or snowy days. |
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