Probably even a child will tell you what precipitation is. Rain, snow, hail … That is, the moisture that falls from the sky to the ground. However, not everyone can clearly say where this water comes from. It is clear that from the clouds (although this is also not a firm rule), but where do the clouds come from in the sky? To understand the cause and nature of the showers, rains and snowfalls passing over our heads, we need to understand the exchange of ash-two-o on planet Earth.
From the surface of the oceans and seas, under the influence of the sun, water evaporates. Invisible to the eye, steam rises up, where it gathers into clouds and clouds. The wind carries them to the continents, where precipitation falls from them. Heavenly moisture falls to the ground, into rivers and lakes, seeps into groundwater, nourishing springs. In turn, numerous streams, rivers and large streams flow into the seas and oceans. This is how the Earth's moisture cycle occurs.– constant circulation of water in its various physical states: vapor, liquid and solid.
It would be a mistake to assume that precipitation must necessarily fall from the sky. In some cases, they appear on objects like dew, hoarfrost or hoarfrost, and even rise from the bottom up, like fog. This is due to the condensation of steam in cold, moisture-saturated air. If the body of water is warmer than the air above it, the evaporating H2O molecules immediately condense and form fog or clouds that bring rain. If the sea is colder than the air, the reverse process takes place: the icy masses of water, like a sponge, absorb moisture from the air, drying it out.
This explains the fact that atmospheric precipitation falls across the Earth's territory extremely unevenly. The warm Gulf Stream carries heated currents from the Caribbean Sea to Iceland in the far north. Getting into the cold air, moisture is intensively released and forms clouds, thereby forming the maritime climate of Western Europe. And off the western coasts of Africa, Australia and South America, the opposite process is happening: cold currents dry up tropical air masses and form deserts, for example, the Namib.
The average rainfall on the planet is approximately 1000 mm per year, but there are regions where the moisture falls much more, and there are places where it does not rain every year. Thus, deserts receive water less than 50 mm in 365 days, and Charrapunja in India holds the record for the abundance of heavenly moisture,which is located on the windward slopes of the Himalayas at an altitude of more than one km above sea level - it rains 12 thousand millimeters per square meter per year. In some places, precipitation is unevenly distributed over the seasons. For example, in the subequatorial climate there are only two seasons: dry and wet. In the Northern Hemisphere from November to May there is a bucket, while in the other 6 months there are showers. During the dry period, only 7% of the annual rate falls.
How is the amount of rainfall from heaven measured? For this, there are special devices at weather stations - rain gauges and pluviographs. These are bowls measuring 1 square meter, into which all heavenly moisture falls, including solid atmospheric precipitation - snow, powder, hail, snow pellets and ice needles. Special sides prevent blowing and increased evaporation of water falling into the bowl. Sensors record the height of accumulated precipitation: during one downpour, per day, month and year. To calculate the level of moisture in large areas, the radar method is used.
