Why is it so rainy. Why is it raining? Places on Earth where they don't know about rain

Or snow. It goes on and on, only the weather is bad, it spoils the mood. Meanwhile, this is an interesting natural phenomenon that it would be useful for everyone to study, because, becoming parents, people often hear such seemingly simple questions: "Why is it raining or is the sun shining?" Little ones don't have to explain everything in detail, but a six- or seven-year-old child is already quite capable of understanding a serious explanation. So it is better to know the answer to the question that the child may ask when reminded of an umbrella and bad weather.

Many people know from their school chemistry course that water can exist in several states of aggregation: solid, liquid and gaseous. Moreover, from a liquid to a gaseous state, it passes almost constantly and the more intensely, the higher its temperature. If you leave a puddle of water on the table, after a while it will dry out - it will evaporate. In the same way, it evaporates from rivers, lakes, from the leaves of plants, soil - from any surface. She got there from the lakes, which are fed by the rain that has passed before. So this one turns into

But in nature, everything is balanced: both on the lid of a pot of boiling water and high in the troposphere, where the air temperature differs significantly from that observed near the earth, condensate forms, that is, drops of water. When they become very heavy, that is, they accumulate a lot, form and then drops fall to the ground under the influence of gravity - it's raining! Water is collected in streams, streams, in the end, its remnants can reach one of the oceans. Everything starts over. Of course, this process is described somewhat simplified, but without serious omissions.

This phenomenon is known as the water cycle or whirlpool in nature. However, the last term is somewhat incorrect, since a whirlpool is usually called another phenomenon that has nothing to do with precipitation.

This whole little story explains why it rains. Sometimes it snows instead, these are drops of water that freeze and become snowflakes - ice crystals. Hail is an even more interesting phenomenon, it occurs when condensate, that is, water droplets, collide with very cold air, then some of them can freeze, but not become snowflakes, but turn into hailstones. Large

hail can form if there is strong air in the cloud, which prevents precipitation for quite a long time. When this cold cloud collides with warmer air, a thunderstorm begins, hail falls. This phenomenon, however, should not be confused with snow pellets or rain with snow - they are significantly different.

After rain, especially if the weather is warm, even hot, you can see a rainbow. When the rain is mushroom, that is, the sun is not hidden behind the clouds, it can be seen right during the rain. It appears when the sun shines through small droplets of evaporating or falling water. This beautiful natural phenomenon is very popular with children, so sometimes the question: "Why is it raining?" - you can even answer: "In order for people to see the rainbow."

Rain formation is directly related to one of the key natural mechanisms of our planet - the water cycle. On Earth there are many rivers, seas and oceans, the water in which tends to evaporate.


This happens under the influence of sunlight: the Sun heats the surface of the water, and the large drops of which it consists turn into tiny ones that form light steam. It rises and enters the atmosphere. Depending on the air temperature, a certain amount of moisture is retained in the atmosphere.

Gradually, it condenses, and clouds form in the sky. Not all of them become rainwater, but sooner or later the accumulated water in vapor or droplet form again falls into water bodies and onto land, from where it either penetrates underground and then again enters water bodies in the form of groundwater, or again evaporates from the surface.

What happens inside the cloud?

Moisture in the clouds is able to travel great distances - it is supported by ascending air currents. Drops of water fall on the ground only after they become large and heavy enough. Inside the cloud, the process of vapor condensation continues: particles of vapor from the air settle on the smallest drops of water.

Droplets inside the cloud move in different directions, collide with each other and connect with each other. But clouds are not only accumulations of a large number of water drops, they are also a mass of tiny ice crystals. If there are only water drops in the cloud, their enlargement occurs very slowly - in one raindrop there are about a million of these tiny droplets of vapor.


And if the cloud is mixed, then water drops are in its lower part. And in the upper, in the area of ​​colder air, the same ice crystals are concentrated in the cloud. Rain in such a cloud forms quite quickly. And sometimes it happens that warm air rises very quickly in summer, and at high altitude, under the influence of negative temperatures, the drops massively turn into pieces of ice and fall to the ground in the form of hail, not having time to melt.

After it starts to rain, new currents of moist air replenish the rain cloud, and this continues until the flow of moisture weakens. In summer, each cubic kilometer of a rain cloud can contain about a thousand tons of water. The largest rain clouds, from which real downpours will spill, are formed on hot days, when a large amount of evaporating moisture rises from the surface of the earth into the air.

The cloud grows, increases in size and gradually its top reaches the cold layers of air. Approximately at an altitude of eight thousand meters above the ground, the air temperature can be up to minus thirty degrees. It is in this extreme cold that vapor drops crystallize into ice.

Often, when we see a dark cloud, we think that now. But the darkest gray clouds can pass by without shedding a drop of moisture. A sure sign that the cloud is really a thunderstorm is its blue-lead hue.

Where on earth does it rain more often?

The frequency and intensity of rains in different parts of the planet depends on the atmospheric pressure belts. At the equator, the air is constantly heated, there is an area of ​​​​low pressure, and warm air, rising up, is regularly cooled.


That is why huge rain clouds constantly form in the equator region and heavy rains fall. This also happens in other parts of the planet, where the climate is determined by areas of low atmospheric pressure. The air temperature is also important: the higher it is, the more often it will rain in this place.

Where high-pressure belts dominate, descending air currents reign. Cool air, descending to the surface of the earth, heats up and becomes less saturated with moisture. In latitudes of 25-30 degrees, it rarely rains, and at the poles there is almost no precipitation.

Moisture Coefficient and Precipitation Observations

The level of humidity in a particular area is usually determined using the moisture coefficient. It is calculated by dividing the annual rainfall by the evapotranspiration over the same time. The lower the humidity coefficient, the drier the climate.

Provided that the annual precipitation is approximately equal to evaporation, the moisture coefficient is close to unity. This pattern is observed in forest-steppes and steppes. If the coefficient is greater than one, then the territory is characterized as an area with excessive moisture. If the coefficient does not exceed 0.3, the territory is characterized as an area with poor moisture - such areas include deserts.


Climate scientists measure the amount of precipitation in a particular part of the planet. Experts recorded an absolute minimum of precipitation - this is the situation in the Libyan Desert and the Atacama Desert, where less than 50 millimeters of precipitation falls per year.

The absolute maximum falls on the Pacific region (Hawaii) and Indian Cherrapunji, where more than 11 and a half thousand millimeters of rain falls every year.

The formation of a cloud begins with the process of vaporization, which in nature occurs constantly. The sun heats the earth and water bodies, and thereby accelerates evaporation. Droplets detached from the water surface are so small that they are held above the ground by warm air currents. Light transparent vapor mixes with air masses and together with them rushes up.

Meanwhile, the evaporation of water from the surface of the soil and water bodies continues. The wind knocks together small flocks of fog. A cloud forms. Tiny droplets of water vapor move randomly, sometimes they merge and become larger during collisions. However, this is not enough to start.

For this to happen, the droplets must become large and heavy enough that the updrafts of air cannot hold them. One raindrop is obtained by merging with a million other cloud droplets. This is a very lengthy process.

Rain clouds form in the troposphere, the lowest layer of the atmosphere. The troposphere is heating up, so the air temperature near the surface of the planet is very different from the temperature a few kilometers above it - it drops by an average of 6 ° C for each rise. Even in the summer heat, at an altitude of 8-9 km above the Earth's surface, downright arctic cold reigns, and temperatures of -30 ° C are not uncommon here.

Processes inside the cloud

Water vapor, rising up along with air currents, gradually cools down, and then freezes, turning into tiny ice crystals. Thus, in the upper part of the rain cloud there are ice crystals, and in the lower part there are water droplets.

Water vapor condenses inside the cloud. As you know, this process is possible only in the presence of any surface. Water vapor settles on water droplets, all kinds of dust particles and motes raised up by ascending air currents, as well as on ice crystals. The size and weight of the crystals rapidly increases. They can no longer stay in the air and break down.

When passing through the thickness of the cloud, the ice crystals become even larger and more weighty as the condensation continues. If the temperature is above zero at the lower boundary of the cloud, the ice floes melt and fall to the ground in the form of rain; if it is below zero, hail occurs.

And then everything starts all over again. Numerous rain streams form that replenish terrestrial reservoirs. Some of the precipitated moisture seeps through the soil and enters underground water bodies. And part of the water evaporates, and a cloud forms above the earth.

Children are very inquisitive. They hope to always receive exhaustive answers to their many questions from adults.

When a child sees rain, on the street, in a picture or in a cartoon, he may have a question: Why is it raining? Where does it come from in the clouds? How is it formed? Why does it fall from the sky?

Rain is one of the stages of the water cycle in nature. When the Sun shines on the Earth, it warms it up. There are many different water bodies on our planet - rivers, lakes, seas and oceans. The light and heat of the sun heat all this water. Part of the water becomes steam. These are very small droplets of water that are difficult to see individually.

We see it when water boils in a pot or kettle. The vapor is very light and therefore it rises into the sky. When there are many small droplets of steam, clouds are obtained that float in the sky, high above our heads. The wind drives them.

As long as the air is warm, nothing happens to them. But, when the air gets colder, the small vapor droplets are attracted to each other and become larger raindrops.

Gradually the clouds become heavy and large. And then they rain down on the Earth.

How to make rain with your own hands?

You can demonstrate a simple experience to a child at home. To do this, put a pot of water on the fire. Hold the lid over the pot. To keep it constantly cold, put pieces of ice on top. As the water heats up, steam will form. It will rise and settle on the bottom of the lid. The vapor droplets will begin to combine. Then the child will see large droplets of water that will drip back into the pan. This will make artificial rain at home.

Yesterday it was pouring, today it is pouring, last week I did not leave the house without an umbrella. Wet forecast for next week. This is summer, right? I'm calling with this question. Yury Varakin, head of the situational center of Roshydromet.

- Yuri Evgenievich, what's the mess?

For the second half of June, we in Moscow and the Moscow region, of course, exceeded the norm for precipitation. Well, let's add it now. So what to do? A powerful cyclone stands north of Syktyvkar and with its waves gives heat on one side, and pumps precipitation on the other. It is rainy not only in the Central strip, but also on the upper Volga, in the northern Urals, on the Black Sea coast of the Caucasus. Gelendzhik, Tuapse, Sochi, Adler are also in the rain.

- But in the past years this was not the case! What's happening?

Year after year is not necessary. This time, unconventional conditions arose for us due to the fact that the previous few weeks there was an abnormal heat over all of Western Europe from England to Spain and Germany. They have heat, we have rain and cold. In theory, at the top of summer in Moscow, the average daily temperature should be 25 degrees and above, and now it is 15 degrees and rainy.

Usually cyclones come to us from the south or from the south-west - and they bring heat. But the heat is "stuck" in Europe. And cyclones began to make their way to us from the northeast, pumping in moisture and cool air. However, they cannot go further. In the region of Kazakhstan and the Volga region - a blocking process. Therefore, all moisture is poured out here.

For vacationers, this, of course, is not good. But for agriculture - a plus. Soil, reservoirs, groundwater are filled with moisture. In the previous summer and at the beginning of this season there was a moisture deficit.

- But there is a feeling of a universal flood ...

Yes, as long as it rains. But so far the climatic norm of July has not been exceeded. In July, precipitation is usually 30 percent more than in June. In general, it’s too early to say that everything was flooded with us.

- Can we already say that this summer will also be anomalous - in terms of heat in Europe, in terms of rain in our country?

Usually it happens - if somewhere is empty, then somewhere is dense. So far, we can only say unequivocally that the scenario of 2010, when there was an incredible heat for a long time, it was dry, fires were blazing, will not happen again. The moisture that the forests received in June and in the first ten days of July is enough to avoid drought and other similar cataclysms.

In general, we assume that the temperature in the first half of July will be only 1-1.5 degrees below the norm. In the second half of the month, there may be days with temperatures above normal. So, on average, July 2015 will not stand out much compared to other years. Although over the past 4-5 years, this July will indeed be one of the coldest and rainiest.

- Did last June fit into the standard framework?

Less than 1 percent of precipitation fell in the first half of June. And in the second - 140 percent. In general, it turned out 120 percent of the norm. It's also not catastrophic.

So far, one third of the monthly rainfall has fallen in July. But now it's only the 12th. And there will be more rain. Moreover, it will be watered with different intensity - there will be days when no more than 1-2 millimeters of precipitation will fall, and it can pour in such a way that 20 millimeters per day will be typed. The ongoing climate change is characterized by the fact that precipitation is very uneven.

- That is, the reason for everything is global weather changes?

Yes. But they do not lead to the fact that globally the whole world immediately floods or to the fact that everywhere it immediately becomes warmer.

On the contrary, according to all classical theories, climate change in the Northern Hemisphere is characterized by the fact that blocking processes occur more often. And they lead to long periods of either dry or rainy weather.

If earlier cyclones moved from west to east for 5-6 days - and after 5 days the sun shone again, now it may not rain for a very long time, and then for three days, or even a whole week, it rains and falls immediately about the monthly norm of precipitation.

And further. If earlier the temperature contrasts in summer between the frontal zones were 5, maximum 7 degrees, now the temperature can drop from 32-35 degrees to 12-15 degrees in a very short time, as it was in Siberia. Yes, and in the suburbs it was recently 30-35, and now the temperature does not exceed 18 degrees.

- Again, everything will be blamed on human activity?

Of course, the anthropogenic factor affects the processes. But the main reason is that the average daily temperature in the Northern Hemisphere is rising at a much faster rate than in the Southern Hemisphere. Plus - the area of ​​​​forests is decreasing, the desert zone is increasing. All this affects climate change in the regions.

- Can we say that the next years will be unusual?

At meetings with employees of the Ministry of Emergency Situations, power engineers, agricultural specialists, we say that in the next 10-15 years we must be prepared for climate change. And many countries are already restructuring their programs. India, for example. China is building or planning to build dams to provide itself with water. Moreover, on transboundary rivers that feed our territory. In particular, together with Mongolia, a dam can be built on one of the large rivers that feed Baikal.

In the next 10 years, the main geopolitical struggle will unfold not for oil, but for water, for fresh resources.

The processes that we are seeing now are just the tip of the iceberg.