Nowadays, any schoolchild knows how rain forms , but still it’s worth refreshing knowledge. Water vapor is an invisible, but always present component of the air surrounding the Earth. In all terrestrial bodies of water, from oceans and seas to small ponds, the process of water evaporation is constantly taking place. From a liquid, it turns into gaseous vapor. The warmer the water, the faster it evaporates, and the larger the area of the reservoir, the more water turns into steam. People do not see this evaporation, water vapor becomes visible where it cools, where condensation occurs, that is, at high altitude. Condensation is the process of turning an invisible vapor into a visible liquid. The main role in this belongs to solar energy. She raises steam high in the sky and turns into clouds. The wind, in turn, carries these clouds over long distances, distributing vital moisture throughout the earth.
Rain mechanism
How do raindrops form? As soon as the cloud is completely saturated and cannot accept moisture, the process of falling of the smallest droplets begins inside it. When falling, they bind to other droplets, which create droplets even more, and as a result, you can observe how rain forms.
During rainfall, large drops are created that can reach 7 mm in diameter. A drop of fine rain is less than half a millimeter. During light rain, the drops practically do not separate, but everything becomes wet. Rain is actually a cloud that drops itself. This is observed when the droplets or crystals from which it is created are made unnecessarily heavy and fall out towards the Earth. Meteorologists identify several methods for turning drops into rain. How rain forms depends on which clouds the drops pass through - warm or cold. Warm clouds are created from tiny particles of water. Falling drops often turn into steam in flight to the ground. And there are so large that they fall to the ground in the form of rain. A tiny droplet passes through the cloud, while it collides with other droplets, and when combined, they create a large drop. Such a drop collects other drops on its way down. The air that sweeps around the speed drop attracts tiny drops, increasing its weight. Sometimes it becomes so heavy that it falls from a height into a puddle.
Where do snowflakes come from?
How frost, rain, snow is formed - all these phenomena are studied by meteorologists and weather forecasters in order to foresee them and in time to warn the population about bad weather. In cold clouds, droplets are born by ice crystals. Cold clouds form high in the sky and are transferred to areas where the temperature is always outside the freezing range (0 ° C). Such clouds are a mixture of water droplets and ice crystals. When water evaporates from liquid droplets, it adjoins the crystals, freezing and turning into a solid. When crystals grow and gain moisture, they turn into snowflakes and fall through the cloud. But if the outside is not too cold, snowflakes do not last long. They descend into layers of warm air and begin to melt, again turning into raindrops. How do snowflakes arise? If the cloud contains zones of different temperature and humidity, it turns into a snow machine. Warm, warm air that carries drops of water with it passes into the dry, cold zones of the cloud. Due to the low temperature, the droplets freeze and form the core of the future snowflake. Particles of warm water gather around the core in a certain order, turning into a snow crystal. Each snowflake consists of 2-200 individual crystals. Crystals form in cold clouds high above the ground, where the temperature can drop to -40 ° C and water vapor freezes, turning into ice. A snow crystal leaves a cloud and falls to the ground. The snow seems crystal clear when it falls, but in fact most snowflakes are created around the tiny particles of dust that the wind brought into the sky, water vapor can crystallize even around small particles of smoke. If you look through powerful microscopes, you can see these particles that hide inside snowflakes. Three quarters of snowflakes have grown around tiny, invisible pieces of clay or earth.
Snowflake shape
Probably, each person had the opportunity to admire the intricate shape of snowflakes, when, gradually descending from the sky, they settle on a mittens or coat. Each snowflake is distinguished by its shape and its own special structure. The main shape of the snow crystalline depends on the temperature at which the snowflake formed. The higher the cloud, the colder it is. From high cirrus clouds, in which the temperature is below -35 ° C, hexagonal prisms are created, when the temperature of the clouds is within -3-0 ° C, plate-shaped snowflakes form. At a temperature of -5-3 ° C, needle-shaped snowflakes form, and from -8-5۫ ° C in the form of columns. At -12-8 ° C, plates are formed again. If the temperature drops below - snowflakes take the form of stars. Growing, snowflakes become heavier and fall in the direction of the earth, their shape changes. If snowflakes fall, rotating, their shape will be perfectly symmetrical; if they fall, swaying to the sides, their shape becomes irregular.
If the air under a snow cloud is warmer than 0 , snowflakes can melt when falling, turning into raindrops, this explains how rain and snow are formed, turning into rain. But if the air is cold enough, the snowflakes will fly to the ground, covering it with a white blanket. Once on the ground, snow crystals gradually lose their sophisticated patterns, being compressed under the influence of other snowflakes.
When does hoarfrost fall?
Hoarfrost refers to solid atmospheric precipitation that falls out with a thin layer of ice crystals. Appears on the ground and objects with freezing soil, quiet wind and clear sky. At a temperature below zero, it precipitates in the form of hexagonal crystals, at a lower temperature - in the form of plates, below -15 ° C, hoarfrost crystals take the form of blunt needles. Frost forms on any objects whose surface is colder than air: on grass, earth, roofs, glass.
Acid rain
Precipitation (rain, snow) with a high acid content is acid rain. How are they formed? Sources of acid rain can be both natural processes (volcanic activity, decomposition of plant residues), and industrial emissions, primarily sulfur dioxide (SO 2 ) and nitrogen oxides (NO, NO 2 , N 2 O 3 ), when various types of fuel. Combining with moisture in the atmosphere, they form sulfuric and nitric acids. If acidic substances dissolve in air and enter an atmosphere saturated with moisture, then the acid falls to the earth in the form of precipitation. If water, including acids, falls on vegetation and on the earth, it harms the flora and fauna of the earth.
Colorful rains
Sometimes people can observe phenomena such as colored rains. Colored rain is rare, but it can actually be colored. How does rain with different colors form? For example, red rain was seen in April 1970 in Thessaloniki in Greece. A powerful wind over the Sahara desert lifted a lot of particles of red clay high into the sky, and then transferred them to the clouds in the sky over Greece. A stream of rain washed the clay from the clouds, but the color of the rain was red for some time. In 1959, a yellow-green rain fell in Massachusetts. The culprit was spring pollen from plants, raised up. And in March 1972, blue snow fell in the French Alps: this snow was stained with minerals brought from the Sahara.