In meteorology, precipitation is water that falls to the earth's surface from the atmosphere in liquid or solid form under the influence of gravity. Therefore, phenomena such as rain, snow, hail are precipitation. Consider the question of how rain, snow, hail, and dew and frost form.
What are clouds and clouds?
Before discussing how rain and other types of precipitation are formed, consider natural objects such as clouds and clouds from the point of view of physics, since they play an important role in the process of precipitation.
Clouds and clouds are a collection of small droplets or crystals of water that are suspended in the atmosphere. Whether a given cloud consists of crystals or small droplets of water depends on the height above the earth's surface of this cloud and the temperature. Clouds are formed as a result of the fact that warm and humid masses near the surface of the water in the seas and oceans rise, cool and condense into small drops. These drops are so small thatvisible to the naked eye. Their combination forms clouds and clouds. If these drops, for one reason or another, begin to increase in size, they will fall to the ground.
Formation of rain
To understand how rain is formed, you should pay attention to the size of the water droplets suspended in the atmosphere that make up the cloud. When these drops begin to collide and connect with each other, then at a certain critical size, gravity will force them to fall down to the ground. At the same time, they acquire a speed of 4 to 8 m/s.
A raindrop has a size of about 1 mm (from 0.7 mm to 5 mm). To reach this size, the cloud droplets must increase their mass millions of times. In this regard, the thickness of the cloud must be greater than a certain size. Some clouds can reach a thickness of 12 km, while they can lead to the formation of powerful and prolonged downpours, and in some cases even hail.
The large thickness of clouds and clouds allows droplets to rise up in their thickness, while connecting with other droplets. As a result of this process, large drops are formed, which fall in the form of rain. Another mechanism that explains how rain is formed is as follows: rising in the thickness of the cloud, a small droplet cools and crystallizes. These crystals fall to the ground, when they fall, they heat up and turn into water.
Virga Phenomenon
Virga is rain that falls in the atmosphere, but does not reach the surface of the earth. This natural phenomenon can be explainedif we consider the issue from the point of view of physics. How does this kind of rain form? The fact is that between a large cloud capable of forming precipitation and the surface of the earth, there may be layers of air masses that will be very hot and dry. In this case, drops of water falling from the thickness of the clouds, when they enter these hot and dry air masses, will simply evaporate again and never reach the surface of the earth.
Snow formation
Let's continue to analyze the question of how rain, dew and snow are formed. Now let's focus on the process of formation of solid precipitation - snow.
Snow is a solid form of water that falls to the surface of the earth in the form of snowflakes. Snowflakes form when small water droplets in clouds cool to temperatures below 0°C and crystallize. In order for snow to form, temperatures are not low enough, there must still be some level of humidity in the atmosphere. There are places on earth that are quite cold, but because of the dry air, it hardly snows.
Formation of hail
Exploring the question of how dew, frost, rain and snow are formed, it is impossible not to mention hail. Unlike snow, which is enough to form low temperatures, hail forms when the temperature is below -15 °C. Since the temperature in the atmosphere decreases with altitude, hail forms at the top of thick clouds where temperatures drop to -50°C. Such cloudscalled cumulonimbus. In their lower part, water is in the form of small liquid droplets, and in the upper part - in the form of ice crystals. These crystals gradually grow due to water droplets rising from the bottom of the cloud due to ascending air currents. When the crystal reaches a critical size, it falls to the ground. Note that not all ice crystals reach the ground, as they melt as they fall.
Dew and frost
Let's finish our consideration of the question of how rain, snow, dew and frost are formed, with a physical explanation of the last two phenomena, that is, the formation of dew and frost.
Both of these phenomena are associated with daily temperature fluctuations in the atmosphere. To understand them, you should know that the solubility of water in gaseous form in the atmosphere depends on temperature. The higher the air temperature, the more water in the form of steam can be dissolved in it. During the day, the sun warms the air and leads to the evaporation of water and an increase in humidity in the atmosphere. At night, the air cools, the solubility of water vapor in it decreases, excess water condenses into small droplets that fall in the form of dew.
Frost forms in a similar way, only in this case either the air temperature drops below zero, which leads to freezing of water droplets in the atmosphere, or the earth's surface is cold enough, and the dew that has fallen on it crystallizes.
