Introduction
Precipitation is an important atmospheric weather phenomenon. There are various types of precipitation which are discussed below (1).
Water particles present in the air combine with each other and form bigger particles. As a result, they can no longer stay suspended in the air and comes down on the surface in solid or liquid form because of gravitation called precipitation. Types of precipitation are rain, snow, sleet, dew, etc.
Precipitation is of two types namely liquid and solid. Liquid precipitation is rainfall. And solid precipitation is snowfall, hail, drizzle, freezing rain, dew, frost, rime, etc. The formation of these precipitations is different and goes through a different process before coming down to earth (2) & (4).
Types of precipitation
Precipitation is the condensation of atmospheric water vapor that finally comes down due to the gravitational force (1). The types of precipitation are
1. Snowfall
Precipitation of white and opaque grains of ice is known as snowfall. These types of precipitation occur when water freezes in the atmosphere. In winter, when the temperature drops below zero degrees celsius, snow falls from the clouds.
In highlands, if cooler air flows, the tiny water particles become cooler and condensed into the snow. When this snow falls to the ground, it is called snowfall (2).
2. Rain
Water evaporates from lands and sea and rises upwards. In high altitudes, due to low temperature, the water vapor in the air is converted into water particles. The water particles get larger when they combine. As a result, these particles can no longer float in the air and comes to the ground this phenomenon is known as rain (1).
3. Sleet
When it rains with snowflakes then such precipitation is known as sleet or ice pellets. It is basically frozen raindrops. Sleet or ice pallets are partially frozen but not crystalline. It occurs from nimbostratus, stratocumulus, and cumulonimbus clouds. And forms mainly during the winter seasons. This type of precipitation can occur when a warm layer of air is above the freezing layer below the surface of the earth (3).
4. Drizzle
Light rain with very fine water particles less than 0.5 mm in diameter is called drizzle. This type of precipitation occurs from stratus and stratocumulus. It falls to the ground very frequently (1).
5. Dew
When the earth’s surface cools by radiating heat at night, the air adjacent to the earth’s surface also cools. Then the water vapor reaches the dew point, it accumulates in the form of tiny water droplets on the surface of the grass, tree or leaves called dew (1).
6. Hail
Due to the upward flow of air, water vapor is often raised by storms. When it comes in contact with extreme cold, the water vapor freezes and turns into solid ice particles. Once these ice particles combine to form large ice particles, they will no longer be able to float in the air. Then the wind speed decreases and the particles of frozen icefall to the surface quickly with rain known as hail (2) & (3).
7. Freezing rain
Freezing rain occurs when the water droplet falls from the clouds does not get enough time to freeze completely before hitting the ground. In another way it can be defined as when a very cold water droplet falls into the ground, it crosses the air layer below the freezing point, or falls on a similar cold surface and accumulates as a water droplet. It usually occurs from the Nimbostratus (4).
8. Frost
In temperate regions, in winter, instead of dew on the leaves or grass of the trees, a soft and cool covering like a piece of white cotton is formed. It is called Frost. Frost is a thin layer of ice (1).
9. Rime
Rime is a type of ice or white snow. It is formed when moisture from a fog suddenly accumulates on an object (2).
Causes of different types of precipitation
1. Snowfall
Water vapor present in the cloud condensed into snow when temperatures drop below the freezing point. The clouds over the cold temperature zone and the high mountain areas are having very cold water particles.
But these water particles do not participate directly in precipitation. Water vapor condenses into ice particles as a result, the latent heat is released. This evaporates the water droplets and makes the air drier. Then, the liquid water disappears and the ice gets larger. These ice are heavy so they cannot float in the air, and falls as snowfall on the surface of the earth (2).
2. Rain
The seawater evaporates and rises upwards. Some water vapor flowing towards the land is obstructed and rises upwards. In both cases, the water vapor in the air under the influence of cold is converted into water particles. Water particles come in contact with each other and form large water particles. These particles are so heavy that they cannot float in the air. Then the water particles fall on the earth’s surface in the form of rain (1).
3. Sleet or ice pallets
Many times the lower layer of the atmosphere is having a layer of cool clouds near the surface of the ground. And the warm cloud layer is located above the cool clouds layer. Water droplets from warm clouds penetrate cold clouds and fall to the earth’s surface, congealing into small ice particles. This is the cause of sleet (4).
4. Drizzle
Drizzle is light liquid precipitation formed from stratus clouds. This type of precipitation is made of very small raindrops. The raindrops are larger than a cloud drop but smaller than a normal raindrop. This type of precipitation usually happens when the cloud updraft is not strong enough to produce rain. Clouds that cause this type of precipitation have low clouds, usually less than 1000 feet high (1) & (3).
5. Dew
Water vapor condenses on the grass or leaves and forms dew of water droplets. At night the surface cools as a result of heat radiation. This cools the adjacent air layer and condenses near the surface. Cloudless skies help to cool the heat at night and increase the cold. In calm weather, slow winds, excessive humidity, water vapor forms water droplets at the top of the grass and accumulates as dewdrops on the leaves of small trees (1) & (2).
6. Hail
The primary cause of hail is extreme heat. When the raindrops fall, they are almost always in the middle of the upward pressure of the wind. As a result, as the raindrops go down, some of them start rising again and become colder. The condensed water droplets become heavier and go down again. Some parts of it may go up again due to the upward pressure of the warm air.
During such ups and downs, some of the water droplets turn into small ice cubes. These are heavier. So these ice cubes can no longer rise. The force of gravity pulls down with the flow of rain. This is how hail is created (2) & (4).
7. Freezing rain
Freezing rain occurs in the winter season. When the water droplets are exposed to a cold layer of the air mass or a surface where the temperature is below 0°C. This results in immediate freezing before falling to the ground in the form of precipitation.
When snow falls, it enters a layer of warm air. Here snow and ice particles break into raindrops. Then raindrops start falling towards the surface. There is a layer of the cold air mass. The raindrops enter this layer and cool to temperatures below 0°C.
This layer is so shallow. These raindrops freeze before they fall to the ground as they pass through the cooling air mass. That is the main cause for freezing rain (1) & (4).
8. Frost
The main cause for frost is that when the temperature drops below freezing, water vapor condenses and forms a thin layer over the surface. Although the normal temperature of the atmosphere is higher than 0°C, the surface and adjacent low air layer cool due to heat radiation and when it reaches 0°C, frost accumulates on the ground. Sometimes water vapor in the air accumulates directly in the form of frost (3).
9. Rime
Crystals of white and clear ice are sometimes formed by the formation of very cold water droplets. The temperature must be below 0°C. Rime formation is ideal for any smooth surface that is on the windward side of the wind (3).
Q&A
1. Which of the following cloud types is most commonly associated with precipitation?
Cumulonimbus clouds are most commonly associated with precipitation.
2. Which is not among the main types of atmospheric lifting and precipitation?
Advective is not among the main types of atmospheric lifting and precipitation.
3. What are the four types of precipitation?
The four types of precipitation are
- Rain
- Snowfall
- Freezing rain &
- Sleet
4. What are the types of precipitation?
There are various types of precipitation. Such as-
- Snowfall
- Rain
- Freezing rain
- Sleet
- Rime
- Drizzle
- Dew
- Frost
- Hail etc.
5. What causes different types of precipitation?
When water droplets fall from the clouds and reach the earth’s surface as precipitation they fall in the form of rain, snow, freezing rain, drizzle, etc. The main cause of these different types of precipitation is the difference in temperature between the cloud base and the ground.
Written By: Manisha Bharati
Reference
1. Savindra Singh. Climatology. Pravalika Publications, Allahabad. Chapter 9: Fogs, Clouds, and Precipitation. Page No: 174 to 201.
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