Precipitation is a long word, but it has a short definition. It is water falling to the ground. However, the scientific definition is a bit different. It is any condensation of atmospheric water vapor left on the ground. Condensation takes place when water vapor (a gas) changes to a liquid.
In many ways, the process of moisture accumulating on the outside of a glass is like the cause of precipitation that falls from the sky. Condensation on the glass usually occurs more often in the summer than other seasons of the year because the humidity is higher, and the temperatures are higher. Humidity is simply the amount of water vapor in the atmosphere (air). In many places during the winter and other seasons, there is usually less moisture and the temperatures are lower, and moisture will not accumulate on the outside of the glass.
There are five main types of precipitation: rain, freezing rain, sleet, hail, and snow. Other forms of precipitation may also include dew, frost, and drizzle. Nevertheless, all types of precipitation have one thing in common-it is a form of water. The type of the precipitation that falls from the sky depends on the temperature and other conditions in the atmosphere, the clouds, and on the ground.
Rain is precipitation that falls to the surface as water droplets and is common almost everywhere in the world. Some places get lots of rain, other places get very little or no rain. Raindrops come in different sizes. The typical raindrop is about 0.5 millimeters or larger, about 1/2 the size of the width of a pinky finger. When the drops are smaller, the rain is called drizzle. A rainstorm is a sudden heavy rain and may cause flooding. Rivers can overflow, and landslides may occur destroying property and causing harm to people.
Rain is caused by the water vapor that builds up in the Earth's atmosphere. Though the water vapor may not be seen, it can be felt as humidity or seen as the clouds form in the sky. Water vapor in the air may become visible as fog too, which are ground-level clouds. The water vapor collects with other substances such as dust, in the clouds too.
Snow is precipitation that falls in the form of ice crystals. The crystals are individually formed in the clouds, but when they begin falling, they stick together in collections of snowflakes. It will snow when the temperatures are below freezing in the clouds and throughout the atmosphere below.
Snowflakes have different patterns based on the temperature and humidity of the air. The ground temperature must also be near or below freezing for the snow to stick. Just like rainstorms, there are also snowstorms, which usually include heavy snow and winds, and sometimes can result in a blizzard, with lightning and thunder.
All the different types of precipitation may fall at the same time during winter storms, especially sleet and rain. There is also a type of precipitation that forms and evaporates before it reaches the Earth's surface. It is called virga.
Hail is basically ice and a collection of frozen water droplets called hailstones. They form in cold storm clouds. The stones can be the size of small rocks, get as large as 6 inches across, and weigh up to one pound. Hailstones may cause damage to cars and homes.
Freezing rain is rain falling from clouds that freezes as it hits the surface of the Earth. Freezing rain sometimes causes the icicles which hang off homes or trees. Sleet is rain falling from the clouds that freezes before it hits the ground. Sleet can sound like tiny stones hitting the top of a car or against a window. Sleet may be described as a mixture of snow and rain.
Finally, two other types precipitation are dew and frost. Dew is a thin film of water condensing on the surfaces of objects near the ground in the early morning or evening. On the other hand, the water or dew, when it freezes, is called frost. Frost is a white powdery substance, forming on surfaces that are very cold. People scrape frost off car windows during cold winter mornings or a white covering on the grass on the outside can be seen.
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