Probably even a child will say what precipitation is. Rain, snow, hail ... That is, that moisture that falls from heaven to earth. However, not everyone can clearly tell where this water comes from. It is clear that from the clouds (although this is also not a hard rule), but where do 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 make ourselves aware of the al-two-o exchange on planet Earth.
From the surface of oceans and seas under the influence of the sun, water evaporates. Invisible steam rises up, where it gathers in clouds and clouds. The wind carries them to the continents, where precipitation falls from them. Heavenly moisture falls on the ground, in rivers and lakes, seeps into groundwater, nourishing the springs. In turn, numerous streams, rivers and large streams flow into the seas and oceans. Thus, the Earth’s water circulation occurs - a constant circulation of water in its various physical states: vaporous, liquid and solid.
It will be erroneous to believe 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 occurs due to the condensation of steam in cold, saturated with moisture air. If the body of water is warmer than the air above it, the evaporated H2O molecules immediately condense - they form fog or clouds that carry rain. If the sea is colder than air, the opposite process occurs: the icy mass of water absorbs moisture from the air like a sponge, draining it.
This explains the fact that precipitation falls over the Earth's territory extremely unevenly. The warm current of the Gulf Stream carries heated streams from the Caribbean Sea to Iceland lying in the far north. Getting into cold air, moisture is intensely released and forms clouds, thereby forming the marine climate of Western Europe. And on the western shores of Africa, Australia and South America, the opposite process occurs: cold currents dry tropical air masses and form deserts, for example, Namib.
The average rainfall on the planet is approximately 1000 mm per year, but there are regions where much more moisture falls, and there are places where it does not rain every year. For example, deserts receive water less than 50 mm in 365 days, and the record for the abundance of heavenly moisture is Charrapunja in India, 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 by season. 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 remaining 6 months there are heavy rains. In the dry period, only 7% of the annual norm falls out.
How to measure the amount of precipitated heavenly moisture? For this, there are special instruments at weather stations - precipitation meters and pluviographs. These are 1 square meter bowls into which all the heavenly moisture falls, including solid atmospheric precipitation - snow, powder, hail, snow groats and ice needles. Special sides prevent blowing and enhanced evaporation of water falling into the bowl. Sensors record the height of accumulated precipitation: during one rainfall, per day, month and year. To calculate the level of moisture in large areas using the radar method.