Does heat cause rain If so, how

How do thunderstorms occur?

A bright lightning flashes in the sky, the clap of thunder can be heard. Rain pelts the earth and in a matter of seconds inundates the land. A thunderstorm is always fascinating. In the past, people feared thunderstorms and believed that angry gods would punish them with it. There was no other way of explaining this natural event. It has long been known how a thunderstorm occurs. Those who stay in the house or in the car and leave the lake or swimming pool in good time need not fear thunder and lightning.

Thunderstorms form when strong sunlight allows water to evaporate and a large amount of warm, humid air rises: a thundercloud is formed. The water droplets in the cloud are swirled far upwards by the buoyancy of the warm air. The drops rub against each other and thereby become electrically charged. Presumably the positive charge collects in the upper part of the cloud, the negative charge in the lower part. This creates ever greater tension, which ultimately discharges in a flash. Electric current flows in the process. The temperature rises to several thousand degrees and makes the flash glow glowingly.

Due to the tremendous heat, the air around the lightning expands with a tremendous bang, similar to an explosion. We call this loud crash thunder. So without lightning there would be no thunder. And because light is faster than sound, the lightning bolt can be seen first and only then the thunder can be heard.

Lightning can shoot back and forth between clouds or from the clouds to the earth. When lightning strikes a building or a tree, the temperature skyrockets to several thousand degrees. The heat can cause severe damage, for example house or forest fires. Before there were lightning rods, thunderstorms were especially feared for this reason.

The water cycle

The water on earth is always on the move. Huge amounts of it are constantly moving - between sea, air and land - in an eternal cycle in which not a single drop is lost.

The motor of the water cycle is the sun: It heats the water of the seas, lakes and rivers so much that it evaporates. Plants also release water vapor into the atmosphere through tiny openings. The humid air rises, tiny water droplets gather in the air and form clouds. As rain, hail or snow, the water falls back into the sea or onto the earth. If it falls on the ground, it seeps into the ground, supplies plants or flows through the ground, via streams and rivers back into the sea. The eternal cycle of evaporation, precipitation and runoff starts all over again.

The water cycle has been around for almost as long as the earth has existed. He ensures that living beings on our planet are supplied with fresh water. And not only that: Without the water cycle, the weather as we know it would not exist.

Precipitation

It doesn't matter whether it's raining, hailing or snowing - it's “to blame” for the clouds. Because without clouds there would be no precipitation. However, it depends above all on the temperature, whether there is a downpour or a wild snowstorm.

Most of the precipitation on earth falls as rain. When small water droplets collide in a cloud, they combine to form larger and heavier droplets. Are they too heavy to float; if the temperature is above 0 ° Celsius, they fall on the earth as rain.

When the air temperature is very low, precipitation no longer falls as rain, but as snow. The snowflakes grow from hexagonal ice crystals that stick together in very cold clouds with water droplets. If the ice formations are big and heavy enough, they dance down from the sky like snowflakes.

If, on the other hand, strong updrafts pull through a towering cloud, there can be hail. Small drops from the lower part of the cloud are swirled upwards, where it is colder than below. There they freeze to form small ice balls, about the size of the heads of a pin. These ice balls are called sleet. If in a very high thundercloud with a strong wind the globules in the cloud are flung up and down several times, more and more raindrops freeze onto the globules. The more the ice balls are driven around in the cloud, the bigger and harder they become. From half a centimeter in diameter, these ice balls are called hail. Hailstones can grow larger than tennis balls and have often already done a lot of damage.

In contrast to precipitation that falls from clouds, there is also precipitation that occurs close to the surface of the earth. If the temperature on the ground drops overnight, the air can absorb less moisture. The excess water then settles on the ground, on plants or on objects: the moisture is clearly visible as dew. If the temperature falls below 0 ° Celsius at night, the water freezes on the objects and forms a whitish layer. Then one no longer speaks of dew, but of frost.

What clouds reveal about the weather

White clouds float in the blue sky like thick cotton balls. Others, on the other hand, tower dark and terrifying. Clouds can look completely different and change constantly. Depending on how and where they appear, they announce different weather. Those who are familiar with the area can tell from the shape of the clouds whether it will soon rain or snow. The height of the clouds also reveals a lot about the upcoming weather.

They are pulling high up, at a height of more than six kilometers above the surface of the earth high clouds. These include the delicate feather clouds that contain many ice crystals. If many of them can be seen, they announce bad weather. Small fleecy clouds and veil clouds, which also consist of ice crystals, float just as high in the sky.

They can be found between two and six kilometers in height medium high clouds, for example the coarse fleecy clouds and the layer clouds. When coarse fleecy clouds stretch over large areas, the weather turns bad. Gray layer clouds also indicate that it will soon rain or snow.

In the lowest "cloud level", under two kilometers above sea level, they move deep clouds. They include the bright heap clouds formed by water droplets. This type of cloud is the most common in the world. Because they bring nice weather, especially in summer, they are often called "nice weather clouds". On the other hand, it can rain or snow from deep gray layer clouds. And the darker the cloud looks, the more rain or snow it carries with it.

Clouds that swell several kilometers high over all three "floors" can carry all types of precipitation with them: Far below the water is not yet frozen, there is rain. However, if the drops are whirled up into higher and colder layers of clouds, ice crystals form. Rain, snow or even hail fall from the towering thunderclouds.

How do clouds form?

How clouds form can be observed particularly well on cold winter days: when you breathe out, the mouth steams - a whitish veil hangs in the air. It forms when the moist, warm air you breathe meets colder air. Because warm air can store a lot of moisture - significantly more than cold air. If the warm air cools down, it can no longer absorb as much water. The excess water then collects into small water droplets that float in the air and become visible as a white veil. It is very similar with the "real" clouds.

The power of the sun heats the land and the water on the surface. The heat turns part of the liquid water into gaseous water: it evaporates. Because warm air is lighter than cold air, it rises. If the warm, humid air cools further upwards, the excess water collects as droplets around tiny dust or soot particles. It is also said that the water condenses. The drops are still so small and light that they float in the air. A cloud has arisen.

So clouds always form when warm air cools down. This can happen when the ground and the air above it warms up and rises. Even if the wind drives the air up a mountain, warmer air is forced upwards. At altitude it cools down, clouds form. The same thing happens when a zone of warm air meets a zone of cold air. The cold air lets the lighter warm air rise and clouds form again!

But it doesn't rain immediately from every cloud. Only when the water droplets combine to form larger drops due to the movement of air and are heavy enough do they fall back on the earth as rain. If the temperature is below 0 ° Celsius, the drops freeze into ice crystals. Then the precipitation falls as snow, in thunderclouds also as small sleet or as large hailstones.

There are also clouds that form just above the earth's surface. This often happens in autumn when the air continues to cool. The whole landscape then appears blurred whitish. If you can see less than a kilometer through this white haze, it is called fog.