We all at least once in our lives thought about the question of why clouds do not fall to the ground. And for an answer, it would be useful to delve into physics, namely, to find out what the sky consists of and what happens above.
Why clouds do not fall to the ground: we learn the secret
The Brown Effect is the answer to why clouds don't fall to the ground!
The visible part of the firmament includes small water droplets and ice crystals. They are in constant motion and collide with each other when interacting with air molecules. This scheme of behavior of molecules and at the same time the answer why clouds do not fall to the ground was put forward by Professor Brown back in 1828, which is why such a movement got its name - Brownian. The degree of intensity of the Brownian effect is determined by several factors:
- drop diameter;
- air temperature;
- resistance force.
Why don't drops fall?
Water particles are at a certain height as long as the dimensions allow warm air to hold them in place, thus explaining why clouds do not fall to the ground. But when the radius of the drop exceeds a micrometer, the Brownian motion stops working and the drop moves down under the influence of gravity. As the speed increases, the droplets begin to enter into resistance with air, gradually reducing the speed of movement.
What happens when the drops start to fall?
The acceleration of falling water drops is proportional to the resistance exerted on them. The latter equals the force of gravity, thereby sharply reducing the speed of the drop. The question of why clouds do not fall to the ground can be explained by the fact that under such circumstances, even the weakest air flow is able to keep a multi-ton cloud at a height.
Where does the rain come from?
In special cases, a drop, due to the accumulation of condensate on the surface or when several units coalesce into one, still falls, since the air flow is no longer able to withstand such a weight. So the clouds do fall, only we call this effect rain and snowfall.
Anyone can understand the laws of physics, so like and share the article with friends for general development. And at the same time read on My Tips - this is important!
Sometimes clouds reach simply colossal sizes - even being on the ground and looking up from a great distance, one can only be surprised at their bizarre shapes and incredible volumes. For those who have not yet received knowledge of their nature, as well as for those who know that clouds are composed of very small water droplets, it often remains incomprehensible why clouds do not fall. How are they kept in heaven?
What are clouds
As much as the reason for the question of why the clouds do not fall, so the rationale for the answer to it will be the knowledge of what these very clouds are.
Each cloud is an accumulation of tiny particles of water in a liquid state or in the form of ice. The size of such droplets can either be quite insignificant - much less than a millionth of a meter (in other words - a micrometer), or reach several millimeters.
However, any small drop is still heavier than air. Why, in this case, only part of the moisture falls in the form of precipitation? How is the remaining mass kept in the sky?
Why don't the clouds fall
A brief answer to this question can be given as follows: clouds remain in the sky due to the interaction of air molecules with water microparticles. For the smallest ones, they set an arbitrary trajectory in the event of a collision, while the larger ones support warm air currents directed towards drops falling under the influence of gravity, resisting their fall and rising to the area of lower temperatures from the heated ground.
If we analyze in more detail why clouds do not fall, then we must first mention Brownian motion - it is characterized by the chaotic movement of the smallest visible fragments of solid matter in a gaseous or liquid medium, which occurs due to a change in the position of the particles of this medium, caused, in turn, by thermal influence . Named after the scientist who discovered this phenomenon - Robert Brown.
Brownian motion - the random movement of microscopic visible particles suspended in a liquid or gas solid caused by the thermal motion of particles of a liquid or gas. It was discovered in 1827 by Robert Brown. Brownian motion never stops. It is associated with thermal motion, but these concepts should not be confused. Brownian motion is a consequence and evidence of the existence of thermal motion.
Brownian motion involves cloud particles smaller than one millionth of a meter. Air molecules push these microdroplets and make them move along an unpredictable trajectory.
Water particles that have reached the size of a micrometer or more are not subject to Brownian motion - they are too large and heavy for air molecules to successfully push them. Such drops begin to fall down under the influence of the force of gravity. However, air resistance acts in the opposite direction, and its strength is proportional to the speed of the drop. Due to this, the drop stops accelerating as it falls and continues to move down at a constant speed. A particle of water flying in this way encounters warm air currents on its way, which can slow down its movement, stop it, or even throw a drop upwards - in the opposite direction.
That's why clouds don't fall to the ground. Consisting of different-sized particles of water, they are kept in the sky due to the peculiarities of the air environment in which they are located.
The role of precipitation in the life of clouds
And what happens to very large and weighty particles of water and drops that do not hang in the air and are not thrown upwards by its streams? Having accumulated in one cloud in large numbers, they turn it into a cloud and fall to the ground as precipitation - rain, snow, hail - or evaporate on the way to the earth's surface.
Also on this journey, the drops can change their size - split into smaller ones or grow, merging with others.
Everyone knows that clouds are made up of small water droplets or ice crystals. Water droplets in a cloud have different diameters - from fractions of a micrometer to several millimeters. No matter how small an ice drop is, it is still heavier than air. Therefore, a natural question arises: how do water drops (and at the same time the cloud as a whole) stay in the air and do not fall to the ground? At the same time, another question arises: under what conditions do water droplets cease to be held in the air and fall to the ground in the form of rain? Let's start with the smallest droplets, the radius of which is fractions of a micrometer. Such droplets are prevented from falling down by chaotic blows from air molecules in chaotic thermal motion. This movement is called Brownian - after the English botanist R. Brown, who discovered it in 1828. Impacts of air molecules force the droplet to bounce in various directions; as a result, it moves along a bizarrely broken trajectory. The heavier the drop, the more difficult it is for air molecules to move it from its place, and, consequently, the less the role brownian motion. But at the same time, the influence of earth's gravity increases. When the droplet radius becomes larger than a micrometer, its motion ceases to be Brownian. The drop begins to fall under the influence of gravity, gradually accelerating. And then a new factor preventing the drop from falling down begins to play an important role - the resistance of the air environment. Simultaneously with the acceleration of the drop, the force of air resistance acting on the drop arises and begins to grow. It is directed opposite to the force of gravity and is proportional to the speed of the drop. As the resistance force increases, the speed of the falling drop increases more and more slowly. When the force of air resistance equalizes in absolute value with the force of gravity, further increase in the speed of the drop stops, and then the drop falls evenly. Such a uniformly moving droplet can be slowed down and even thrown up by an ascending stream of warm air. And the earth, which is heated by the sun, is a constant source of such ascending air currents. In addition, in the process of falling, a drop can simply evaporate. Or break up into smaller droplets. But a drop can, on the contrary, grow larger: merge with others or condense additional steam on its surface, and then it will still fall to the ground. This is how precipitation falls. In a sense, it can even be said that precipitation (rain or snow) is the fall of clouds to the ground, but in reality, raindrops or snowflakes are too large and heavy to be the constituents of clouds. If you look at a cloud from the side during rain, it seems that it falls to the ground.
Light, fluffy and airy clouds - they pass over our heads every day and make us raise our heads up and admire the bizarre shapes and original figures. Sometimes an amazing kind of rainbow breaks through them, and sometimes - in the morning or in the evening during sunset or sunrise, the clouds illuminate the sun's rays, giving them an incredible, breathtaking shade. Scientists have been studying air clouds and other types of clouds for a long time. They gave answers to questions about what kind of phenomenon it is and what clouds are.
In fact, it is not so easy to give an explanation. Because they consist of ordinary water droplets, which warm air lifted up from the surface of the Earth. Most a large number of water vapor is formed over the oceans (in one year, water evaporates here at least 400 thousand km3), on land - four times less.
And since it is much colder in the upper layers of the atmosphere than below, the air there cools rather quickly, the steam condenses, forming tiny particles of water and ice, as a result of which white clouds appear. It can be argued that each cloud is a kind of moisture generator through which water passes.
The water in the cloud is in gaseous, liquid and solid states. The water in the cloud and the presence of ice particles in them affect appearance clouds, its formation, as well as the nature of precipitation. It is the type of cloud that determines the water in the cloud, for example, shower clouds have the largest amount of water, while nimbostratus clouds have this figure 3 times less. The water in the cloud is also characterized by the amount that is stored in them - the water reserve of the cloud (water or ice contained in the cloud column).
But everything is not so simple, because in order to form a cloud, droplets need condensation grains - the smallest particles of dust, smoke or salt (if we are talking about the sea), to which they must stick and around which they must form. This means that even if the composition of the air is completely supersaturated with water vapor, without dust it will not be able to turn into a cloud.
What form the drops (water) will take depends primarily on the temperature indicators in the upper atmosphere:
- if the air temperature of the atmosphere exceeds -10°C, white clouds will consist of water droplets;
- if the temperature indicators of the atmosphere begin to fluctuate between -10 ° C and -15 ° C, then the composition of the clouds will be mixed (drop + crystalline);
- if the temperature in the atmosphere is below -15°C, white clouds will contain ice crystals.
After appropriate transformations, it turns out that 1 cm3 of the cloud contains about 200 drops, while their radius will be from 1 to 50 microns (the average values are from 1 to 10 microns).
Cloud classification
Everyone must have wondered what clouds are? Clouds usually form in the troposphere, the upper limit of which is at a distance of 10 km in polar latitudes, 12 km in temperate latitudes, and 18 km in tropical latitudes. Often other species can be seen. For example, mother-of-pearl are usually located at an altitude of 20 to 25 km, and silver - from 70 to 80 km.
Basically, we have the opportunity to observe tropospheric clouds, which are divided into the following types of clouds: upper, middle and lower tiers, as well as vertical development. Almost all of them (except the last type) appear when humid warm air rises.
If the air masses of the troposphere are in a calm state, cirrus, stratus clouds form (cirrostratus, altostratus and nimbostratus) and if the air in the troposphere moves in waves, cumulus clouds appear (cirrocumulus, altocumulus and stratocumulus).
Upper clouds
These are cirrus, cirrocumulus and cirrostratus clouds. The cloud sky looks like feathers, waves or a veil. All of them are translucent and more or less freely pass the sun's rays. They can be both extremely thin and quite dense (pinnately layered), which means that it is harder for light to break through them. Cloudy weather signals the approach of a heat front.
Cirrus clouds can also occur above clouds. They are arranged in stripes that cross the vault of heaven. In the atmosphere, they are located above the clouds. As a rule, precipitation does not fall out of them.
In middle latitudes, white clouds of the upper tier are located, usually at an altitude of 6 to 13 km, in tropical latitudes - much higher (18 km). In this case, the thickness of the clouds can range from several hundred meters to hundreds of kilometers, which can be located above the clouds.
The movement of clouds of the upper tier across the sky primarily depends on the wind speed, so it can vary from 10 to 200 km/h. The sky of the cloud consists of small ice crystals, but the weather of the clouds does not practically give precipitation (and if it does, then measure them on this moment there is no way).
Mid-tier clouds (from 2 to 6 km)
These are cumulus clouds and stratus clouds. In temperate and polar latitudes, they are located at a distance of 2 to 7 km above the Earth, in tropical latitudes they can rise a little higher - up to 8 km. All of them have a mixed structure and consist of water droplets mixed with ice crystals. Since the height is small, in the warm season they mainly consist of water droplets, in the cold season - of ice droplets. True, precipitation from them does not reach the surface of our planet - it evaporates on the road.
Cumulus clouds are slightly transparent and are located above the clouds. The color of the clouds is white or gray shades, darkened in places, having the form of layers or parallel rows of rounded masses, shafts or huge flakes. Hazy or wavy stratus clouds are a veil that gradually covers the skies.
They form mainly when a cold front pushes a warm front up. And, although precipitation does not reach the ground, the appearance of middle-tier clouds almost always (except, perhaps, turret-shaped ones) signals a change in the weather for the worse (for example, to a thunderstorm or snowfalls). This happens due to the fact that cold air itself is much heavier than warm air and moving along the surface of our planet, it very quickly displaces heated air masses up - therefore, because of this, with a sharp vertical rise in warm air, first white clouds of the middle tier are formed, and then rain clouds whose sky clouds carry thunder and lightning.
Lower clouds (up to 2 km)
Stratus clouds, rain clouds and cumulus clouds contain water droplets that freeze during the cold season and turn into particles of snow and ice. They are located rather low - at a distance of 0.05 to 2 km and are a dense, uniform low overhanging cover, rarely located above clouds (other types). The color of the clouds is grey. Stratus clouds are like large shafts. Cloudy weather is often accompanied by precipitation (light rain, snow, fog).
Clouds of vertical development (conventions)
Cumulus clouds themselves are quite dense. The shape is a bit like domes or towers with rounded outlines. Cumulus clouds can become broken in gusty winds. They are located at a distance of 800 meters from the earth's surface and above, the thickness is from 1 to 5 km. Some of them are able to transform into cumulonimbus clouds and settle above the clouds.
Cumulonimbus clouds can be at a fairly high altitude (up to 14 km). Their lower levels contain water, the upper ones contain ice crystals. Their appearance is always accompanied by showers, thunderstorms, in some cases - hail.
Cumulus and cumulonimbus, unlike other clouds, are formed only with a very rapid vertical rise of moist air:
- Humid warm air rises extremely intensively.
- At the top, water droplets freeze, the upper part of the cloud becomes heavier, lowers and stretches towards the wind.
- A quarter of an hour later, a thunderstorm begins.
upper atmosphere clouds
Sometimes in the sky you can observe clouds that are in the upper atmosphere. For example, at an altitude of 20 to 30 km, mother-of-pearl sky clouds form, which consist mainly of ice crystals. And before sunset or sunrise, you can often see silvery clouds that are in the upper atmosphere, at a distance of about 80 km (it is interesting that these celestial clouds were discovered only in the 19th century).
Clouds in this category may be located above the clouds. For example, a cap cloud is a small, horizontal and altostratus cloud that is often located above clouds, namely above cumulonimbus and cumulus. This type of cloud can form above an ash cloud or a fire cloud during volcanic eruptions.
How long do clouds live
The life of clouds directly depends on the humidity of the air in the atmosphere. If it is small, they evaporate rather quickly (for example, there are white clouds that live no more than 10-15 minutes). If there are many, they can hold out for quite a long time, wait for the formation of certain conditions, and fall to the Earth in the form of precipitation.
No matter how long a cloud lives, it is never in an unchanged state. The particles that make it up are constantly evaporating and reappearing. Even if outwardly the cloud does not change its height, in fact it is in constant motion, since the droplets in it descend, pass into the air under the cloud and evaporate.
Cloud at home
White clouds are pretty easy to make at home. For example, one Dutch artist learned how to create it in an apartment. To do this, he released a little steam from the smoke machine at a certain temperature, humidity level and lighting. The cloud, which turns out to be able to hold out for several minutes, which will be quite enough to photograph an amazing phenomenon.
Good question. Because, as is known from school textbooks, clouds consist of small droplets of water and tiny ice crystals, which, one way or another, are heavier than air.
How do they keep up? Where is the notorious terrestrial gravity? And why does this holding end quite often in the form of raindrops?
The theory of continuous motion, nicknamed Brownian, based on the fact that droplets with a radius of fractions of a micrometer are prevented from falling by air molecules knocking on them, giving these droplets random movement, explains only part of the problem, but far from all.
Why does this drop suddenly become larger in size and weight, and air molecules are no longer able to push it from its place? It is clear that when the movement of the droplet stops and it stops, it begins to fall. That's when the earth's gravity turns on - when the droplet stops. But then the air resistance kicks in... It's like a circus performance when a cyclist or motorcyclist rides on vertical surfaces. If they stop, they will fall. But when they go, they don't fall. They are kept, practically, on weight, by movement ...
They say that clouds, consisting of droplets and ice crystals, "keep" in weight and do not allow ascending air currents from the earth heated by the sun to fall. Because, they say, birds can soar above the ground without flapping their wings.
What keeps clouds in the sky when it's night? And still moonless? And if, say, an eagle urgently needs to fly somewhere on business, will he constantly have to flap his wings at night, like a mad or not yet fledged flyer?
It is believed that the clouds are still falling. In the form of rain or snow. However, snowflakes and, even more so, raindrops are too heavy to be components of clouds. That is, completely different bodies fall out of one body or object. This happens in fairy tales. Or when performing a trick by an illusionist...
Or maybe a cloud is not an object at all, but a process that is constantly taking place. And we see what we see, that is, what we are allowed to see. For if we see the essence of the process, we will either not understand a damn thing, or we will come into contact with the unknown and see the face of God, which is absolutely unacceptable for people.
Or maybe the clouds do not fall to the ground, because they just know how to fly?
Maybe that's how it was originally intended? After all, if they could fall to the ground, many of us would get kirdyk if we got under so much ice and water. And this was not provided for in the plans of the Creator. For the human soul must endure trials, and not so, at once, be freed from all troubles and worries, being buried with the body under tons of water and ice.
Or maybe it is a live picture drawn or projected for us on the celestial sphere, such as 3D? Like rainbows or stars. The rainbow sparkles and shimmers with colors, the stars glow and twinkle. And the clouds float, take on different forms, and look like animals, birds and even people. And all this so that we would not be so sad on Earth. After all, what is drawn does not fall ...
