Water cycle in nature- This is the continuous movement of water under the influence of solar energy and gravity. The importance of the water cycle is great, since it not only unites all parts of the hydrosphere, but also connects with each other all the shells of the Earth (atmosphere, lithosphere, biosphere and hydrosphere).

During the cycle, water can be in three states: liquid, solid, gaseous. It carries a huge amount of substances necessary for life on Earth.

Under the influence sun rays The world's oceans and land are warming. As a result, water changes from liquid to gaseous (steam) and rises. The ocean supplies 86% of the moisture in the atmosphere, and only 14% of vaporous moisture is formed by evaporation from land. The water that evaporates from the surface of the ocean is fresh. Thus, the ocean can be considered a colossal factory of fresh water, without which life on Earth cannot exist. It is known that the temperature in the atmosphere decreases with altitude. Water vapor, meeting all the colder layers of air, begins to cool and form clouds. On land, water evaporation occurs not only from the surface of streams, rivers and lakes. Water vapor enters the atmosphere as a result of volcanic activity and is evaporated by the surface of plants.

Often, water that has evaporated from the ocean returns to it in the form of precipitation that falls from clouds located above the seas and oceans. This is what happens small water cycle in nature (Figure 1).

Rice. 1. Small water cycle diagram

At great water cycle in nature, part of the clouds is transported to the mainland by the influence of the wind (Figure 2).

There, they can also precipitate in liquid or solid form. Part atmospheric precipitation ends up in rivers. They, flowing into each other, ultimately carry water into the seas of the World Ocean or into closed reservoirs such as the Caspian or Aral Seas, replenishing their losses due to evaporation. Another part of the water that falls to the ground in the form of precipitation seeps down from the surface of the land and flows with groundwater back into the World Ocean or rivers. This is a very important stage in the water cycle as it regulates river flow over time. If it were not there, there would be water in the rivers only during short periods of precipitation or melting snow.

A third of the water that falls to the ground in the form of precipitation can penetrate the soil, and from there rise along the roots of the plant and evaporate through the leaves. This stage of the cycle is very important for plants, since dissolved substances enter with water from the soil through the roots. minerals, necessary for plant life.

Rice. 2. Diagram of the large water cycle

In the diagrams shown (Fig. 1, 2):

z – evaporation layer (index “o” - refers to the ocean, index “c” - refers to land), which is the ratio of the total volume of evaporated water () to the area of ​​the globe (), mm.

x, y – denote, respectively, the layers of precipitation and runoff, which are also calculated through the ratio of volumes to the area of ​​the globe.

The equation water balance for the ocean:

z o = x o + y (2)

Water balance equation for land:

x c = z c + y (3)

By solving equations 2 and 3 together, we can obtain world water balance equation:

z o + z c = x o + x c (4)

When studying hydrological processes on land, it is important to consider that land is divided into two areas:

The area of ​​external drainage (80% of the land), from where precipitation enters the World Ocean and which is drained by the largest rivers of the world.

The area of ​​internal flow (20%), which is drainless and does not provide flow into the World Ocean, for example: the Caspian, Aral, Balkhash basins, the Gobi, Sahara, Kalahari deserts, etc. There are also large rivers: Volga, Amu Darya.

The main watershed of the globe divides the entire land into two slopes:

1) with flow into the Atlantic and Arctic oceans (60% of land) and

2) with flow into the Pacific and Indian oceans.

The watershed runs across America from Cape Horn through the Andes to the Bering Strait, then along the eastern highlands of Asia in a latitudinal direction and continues along the eastern edge of Africa and its southern tip.

Not all water returns from land to the ocean at the same time. In the process of the water cycle in nature, a gradual renewal of water occurs in all parts of the geographical envelope:

Groundwater renews itself over hundreds, thousands and millions of years;

Cover glaciers - for several thousand years (in Antarctica - for tens of millions of years);

The waters of the World Ocean - for 2.5-3 thousand years;

Closed drainless lakes - for 200-300 years;

Flowing lakes - over several years;

Rivers – 12-15 days;

Atmospheric water vapor – for 8 days;

Water in organisms – in a few hours.

Human activity has recently begun to play a significant role in the water cycle in nature. The destruction of forests, drainage and irrigation of lands, the creation of reservoirs and dams, the use of water for economic needs - all this has significantly changed the hydrological processes on Earth. And although economic activity had little effect on the total volume of the hydrosphere; it significantly affects its individual parts. The flow of some rivers has decreased, others have increased, and the intra-annual distribution of flow has changed.

As a result of the withdrawal of water from land waters, evaporation has increased in many areas of the world, because it is for evaporation that a significant part of the water withdrawn by humans from sources goes to evaporation. Part of the water that a person consumes and which is part of the products he produces falls out of the general circulation for a long time, which is why it is called “irretrievably withdrawn.” This term, of course, is quite conditional, since this water is not completely excluded, but its return may occur with a large delay in time and in a completely different area.

Another problem is the pollution of large volumes of water as a result of human economic activities. It is the threat of water pollution that now poses the main danger, much greater than the threat of physical water shortage. Polluted water entering the World Ocean during the water cycle leads to the death of living organisms and disruption of biological balance.

Line UMK O. A. Klimanova, A. I. Alekseeva. Geography (5-9)

Geography

Water cycle in nature

It is difficult for a resident of arid desert regions to believe that from space the Earth looks like a huge blue ball, since ¾ of the planet’s surface is occupied by water. All the waters of the planet are called hydrosphere or water shell of the Earth. The water shell includes the World Ocean, rivers, lakes, glaciers, underground and groundwater, swamps, gases and evaporation.

"Water is the juice of life."

Leonardo da Vinci

The planet consumes 14 trillion liters of water every day, and if water supplies were not renewed, the beautiful blue planet would turn into a lifeless desert, like our closest neighbor, blood-red Mars.

Water cycle in nature allows biological diversity of flora and fauna, including humans, to live, grow, and reproduce. The importance of water is difficult to overestimate. It participates in chemical, physical, and biological processes occurring in a living cell.

Desert nomads repeat: “Water is more valuable than gold.” And it is true. A wandering traveler cannot live more than a week without water. After all, the human body is approximately 70%, and a newborn baby - 85% - consists of water.

The water cycle or hydrological cycle occurs due to the ability of water to change its state of aggregation. But as we know, to change the state of aggregation of a substance, energy is needed. And the Sun provides energy for continuous processes world water cycle.

The complete hydrological cycle includes several stages:

Evaporation- the transformation of water from liquid to gaseous due to the energy of sunlight. This process occurs every day: on the surfaces of rivers and oceans, seas and lakes, as a result of sweating of a person or animal.

Steam condensation. In contact with cold air currents, the steam releases heat and then turns into liquid. Drops of dew on the grass in the early morning, autumn fog in the lowlands, or clouds in the blue sky are the visible result of condensation.

Precipitation on the ground. Colliding with each other and undergoing condensation processes, drops of water in the clouds become heavier and fall to the surface of the planet. Due to the high speed, they do not have time to evaporate. And the result is rain, snow or hail.

Passage of water through soil layers. Falling to the ground, some of the water seeps through the soil, feeding the roots of trees, and then enters underground streams. Some of the water falls directly into the sea in the form of precipitation. The rest of the liquid accumulates and is delivered to the waters of the World Ocean using wastewater.

The workbook is part of the teaching materials on geography and is intended for use when working with the textbook edited by O. A. Klimanova “Geography. Geography. 5–6 grades." Contains a variety of tasks aimed at consolidating basic knowledge and skills in the course, as well as tasks for preparing for the Unified State Exam and the Unified State Exam.

In a simplified version, imagine How does the water cycle occur in nature? Three main steps will help:

evaporation of water from the surface of the earth;

condensation and concentration in atmospheric layers ;

the fall of precipitation as rain, snow, or steam back to the ground.

The textbook “Geography 5-6th grade”, edited by O. A. Klimanova, raises a serious question, which we invite you to think about. If water does not disappear anywhere and participates in an endless cycle, why do problems arise with fresh water supplies?

Water cycle diagram shown in the illustration:

There are several types of hydrological cycles in nature:

1. World, or great cycle.

Water evaporates from the surface of the ocean, turning into water vapor, and is transported to the continents by air currents. It falls to the ground in the form of rain, snow and other atmospheric precipitation and returns to the ocean as runoff water. With a large cycle, the composition and quality of water changes. By evaporating, polluted water is purified, and salty water is deprived of salts and turns into fresh water.

2. Oceanic or small cycle. Water that has evaporated above the ocean surface falls back into the ocean as precipitation.

3. Inland gyre. The water that evaporates above the land surface condenses and falls back onto land in the form of rain, fog or snow.

The rate of circulation does not depend on the rate of condensation and precipitation, but on evaporation from the surface of the seas and oceans, as well as plant leaves. Since the surface of the ocean due to accidents on tankers, oil rigs and other man-made disasters becomes covered with an oil film, and the planet's forests are cut down, evaporation decreases, and, as a result, precipitation decreases.

As a result, scientists are seriously concerned that climate change will lead to even greater drought in dry areas, and increased rainfall in swampy and wet areas.

The water cycle is not an isolated process, but part of the global biological cycle of matter and energy, which can be read about on page 123 in the textbook “Geography 5-6th grade” edited by O. A. Klimanova.

Methodological advice

To visualize the water cycle, perform a simple experiment: cover a glass of water tightly cling film and on a sunny day place it on the windowsill. After a while, you will notice how the liquid condenses on the film, and then heavy drops, breaking away from the film, fall into the glass, reminiscent of rain.

In nature, also known as the hydrological cycle, describes the continuous movement of water on, above, and below the Earth's surface. Although the balance of water on Earth remains essentially the same over time, individual water molecules can move in and out of the atmosphere. Water moves, for example, from a river to the ocean or from the ocean to the atmosphere, using such physical processes, such as evaporation, condensation, precipitation, infiltration, runoff, and also through underground flows. In this case, water passes through different phases: liquid, solid (ice) and gaseous (steam).

The water cycle in nature involves heat exchange, which leads to temperature changes. For example, when water evaporates, it absorbs heat from its surroundings and cools it. When it condenses, it gives off heat and heats environment. This heat exchange affects the climate. The water cycle in nature is also associated with geological processes on Earth (erosion and sedimentation). And finally, thanks to it, life is maintained on Earth.

Description

The water cycle in nature begins to be described for children in primary school, so everyone knows that the sun, thanks to which it occurs, heats the water in the oceans and seas. The water evaporates and enters the air as steam. Ice and snow can sublimate directly into water vapor, bypassing the liquid phase. Water also evaporates from plants and soil.

The air raises steam into the atmosphere, where low temperatures causing it to condense into clouds. Air currents are carried around the world, clouds collide, grow and water falls from upper layers atmosphere in Some of this can accumulate in the form of ice caps and glaciers, which retain frozen water for thousands of years. Most of the water returns to the oceans or land as rain, forming runoff. Part of the runoff ends up in rivers, and from there into the seas and oceans. Stormwater and groundwater are partially collected in freshwater lakes. However, most is absorbed into the ground and infiltrated: it penetrates deep into the ground and replenishes aquifers, which are reservoirs. Such aquifers can be located close to the surface, and water can seep back - this is how springs are formed. However, over time, the water returns to the ocean where it all began.

The processes through which the water cycle occurs in nature:

Precipitation

Most precipitation falls as rain. Other types: snow, hail, fog, pellets and sleet. About 505,000 km³ of water falls in the form of precipitation per year.

Sediment interception

Precipitation that is intercepted by plant foliage ends up evaporating back into the atmosphere rather than falling to the ground.

Melt water

Runoff from melting snow.

Stock

The different ways in which water moves through the earth. This can be either surface runoff or underground. Water can seep into the ground, evaporate into the air, be stored in lakes and reservoirs, or be used for agricultural and other purposes.

Infiltration

Seepage of water from the surface into the ground.

Underground streams

The flow of water underground, in the vadose zone and aquifers. Groundwater may return to the surface or eventually seep into the ocean. Groundwater tends to move slowly and replenish slowly, so it can remain in aquifers for thousands of years.

Evaporation

The transformation of water from a liquid into a gaseous state, during which it moves from the surface of the earth or bodies of water into the atmosphere. The source of energy for evaporation is primarily solar radiation. Total evaporation - about 505,000 km³ of water per year.

Sublimation

Transition directly from the solid phase (snow or ice) to water vapor.

Deposition

This is the transformation of water vapor directly into ice.

Advection

The movement of water - in solid, liquid or gaseous form - through the atmosphere.

Condensation

The transformation of water vapor into liquid water droplets in the air, the formation of clouds and fog.

Evaporation

The release of water vapor from plants and soil into the air.

Seepage

The flow of water horizontally through soil and rock under the influence of gravity.

The water cycle in nature occurs thanks to solar energy. 86% of global evaporation occurs from the ocean surface.

The water cycle in the biosphere is a biogeochemical cycle, because... runoff is responsible for almost all of the movement of eroded sediments and phosphorus from land to bodies of water.

The importance of the water cycle is great, since it not only unites parts of the hydrosphere, but also connects everything with each other: the hydrosphere, etc. During the cycle, water can be in three states: liquid, solid, gaseous. It carries a huge amount of substances necessary for life on Earth.

Under the influence of sunlight, the land also heats up. As a result, water changes from liquid to (steam) and rises. The ocean supplies 86% of the moisture in the atmosphere, and only 14% of vaporous moisture is formed by evaporation from land. The water that evaporates from the surface of the ocean is fresh. Thus, the ocean can be considered a colossal factory of fresh water, without which life on Earth cannot exist. It is known that the temperature in the atmosphere decreases with altitude. Water vapor, encountering increasingly cold layers of air, begins to cool and form. On land, water evaporation occurs not only from the surface of streams and lakes. Water vapor enters the atmosphere and, as a result, is evaporated by the surface of plants.

Often, water that has evaporated from the ocean returns to it in the form of precipitation that falls from clouds located above the seas and oceans. Another part of the clouds is transferred to the mainland under the influence. There, they can also precipitate in liquid or solid form. Some ends up in rivers. They, meandering and flowing into each other, ultimately carry water into the seas or into closed bodies of water such as or, replenishing their losses due to evaporation. Another part of the water that falls to the ground in the form of precipitation seeps down from the surface of the land and flows back into the World Ocean or rivers. This is a very important stage in the water cycle as it regulates over time. If it were not there, there would be water in the rivers only during short periods of precipitation or melting snow. A third of the water that falls on the ground in the form of precipitation can penetrate into the plant, and from there rise through the roots to the top of the plant and evaporate through the leaves. This stage of the cycle is very important for plants, since dissolved substances necessary for the life of plants are supplied with water from the soil through the roots. Plants cannot eat dry food.

Not all water returns from land to the ocean at the same time. It lingers the longest (hundreds and thousands of years) in deep-lying areas.

Water returning from land can evaporate again and fall back onto land. This is how its cycle occurs: ocean - atmosphere - land - ocean. This continuous process of moving water from the ocean to land through the atmosphere and from land to the ocean is called the global water cycle in nature.

Human economic activity has recently begun to play a significant role in the water cycle in nature. The creation of industry, the plowing of vast territories, the drainage of lands, the creation of giant dams, the use of water for various economic needs - all this has significantly changed the hydrological processes on Earth. And although economic activity has had little effect on the total volume of the hydrosphere, it significantly affects its individual parts. The flow of some rivers has decreased, others have increased, and the intra-annual distribution of flow has changed. As a result of the withdrawal of water from land waters, evaporation has increased in many areas of the world, because it is for evaporation that a significant part of the water withdrawn by humans from sources goes to evaporation. Part of the water that a person consumes and which is part of the products he produces falls out of the general circulation for a long time, which is why it is called “irretrievably withdrawn.” This term, of course, is quite conditional, since this water is not completely excluded, but its return may occur with a large delay in time and in a completely different area. Many industries use relatively little water irrevocably - no more than 10%. The rest of the water is discharged into water bodies as wastewater after use. They are contaminated and render unusable many times the volume clean water. It is the threat of pollution

Water is the basis of all life on Earth. The amount of liquid on the planet does not change throughout the existence of the world, but the water cycle in nature occurs continuously. Without this process, life would not exist on Earth.

The water cycle gives rise to many curious circumstances. Here are the most interesting facts:

1. Pierre Perrault, who built the Louvre’s water supply system, began to talk about hydrocirculation back in the 17th century. It took two centuries before scientists proved that the water cycle works like this:

• water evaporates from oceans, reservoirs and the earth's surface;
• steam rises into the atmosphere and moves with air currents to different parts of the planet;
• In cold areas, condensation occurs and moisture falls down in the form of precipitation or dew.

2. As a result of the cycle, the water is purified, changes its composition and appearance (salty becomes fresh, ice turns into liquid, drops lose or are filled with microelements). As water circulates, it carries beneficial components, but microbes and viruses travel along with the moisture. 85% of known diseases can be contracted through water.

3. Water is completely renewed in the atmosphere in a week and a half, and in the ocean in 3.5 thousand years. The raindrops you see were in the ocean about 2 months ago.

4. Water in nature moves due to the Sun and gravity. In addition to the atmosphere, water is carried by rivers, underground currents and living organisms.

5. Approximately 306 billion liters of water per day are poured onto the earth from the atmosphere. The most precipitation falls on the Hawaiian island of Kauai (the average amount is 11,684 mm per year, and this is just one of the records). And in the desert the rain evaporates without ever reaching the sand.

6. The use of water by humanity does not reduce its amount in nature. Resources used by people participate in circulation and end up back into water bodies and soil. Pollution is harmful because the chemicals and heavy metals with which we “charge” the water are carried throughout the atmosphere, seas and oceans. Acid rain is the result of human negligence.

But in nature there is no absolutely pure (distilled) water. Only a person can make it like this.

7. The water in the ocean is not only salty, but also nutritious thanks to plankton. Scientists claim that in terms of nutritional value only Atlantic Ocean It is estimated at 20 thousand crops, which are harvested throughout the year throughout the land.

8. The water cycle contributes to the thermoregulation of the earth's spheres and affects the climate. Greenhouse effect disrupts water circulation. Some scientists argue that glaciers are melting, precipitation is increasing, and as a result the planet will overflow with water. Others believe that rising temperatures increase evaporation, so the Earth is at risk of drought.

9. B human body 70% water. Having lost 1%, we feel thirsty. And a 20% lack of fluid is fatal.

10. The water cycle is not only about movement on the surface of the planet. Underground flows are a huge reservoir of fluid that moves and interacts with external environment(replenished by rains through the ground, splashes out through geysers, springs, streams in valleys and ravines).

The water cycle is a natural phenomenon, the key to our existence. Caring attitude people's access to water resources will help nature preserve it unique property to give and support life on the planet.