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If water from the clouds accumulates in the sky, why doesn't it fall all at once, like a waterfall? The physics and chemistry of the atmosphere explain this natural phenomenon!
Rain is a natural phenomenon essential for maintaining life on Earth. But why does it fall in small drops and not continuously?
This question leads us to a deeper understanding of the physics of water in the atmosphere and the water cycle, which is fundamental to the balance of our planet.
The water cycle and cloud formation
Water on Earth is constantly moving between the oceans, rivers, atmosphere and soil. This cycle, known as the water cycle, involves processes such as evaporation, condensation and precipitation.
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Evaporation transforms liquid water from seas, lakes and rivers into vapor, which rises into the atmosphere. This vapor cools and condenses when it encounters lower temperatures, forming small droplets that make up the clouds.
Clouds can be formed by ice crystals or water droplets, depending on the altitude and air temperature.
Some of these clouds, such as nimbus and cumulonimbus, are responsible for heavy rainfall. But how exactly does the water in these clouds turn into raindrops?
The role of condensation nuclei
In order for water vapor to form droplets, it needs surfaces to attach itself to. These surfaces are called condensation nuclei and can be made up of dust particles, pollen or other aerosols suspended in the atmosphere.
These tiny particles allow moisture in the air to aggregate, forming microscopic droplets that grow over time.
When these droplets reach a sufficient size and weight to overcome air resistance, they begin to fall towards the ground.
During this process, many smaller droplets join together with larger ones through coagulation, becoming larger raindrops.
The size and shape of raindrops
Raindrops can vary in size, but they rarely exceed 5 millimeters in diameter. This is because friction with the air causes larger drops to break into smaller ones. This phenomenon is the result of the balance between the surface tension of water and air resistance.
Surface tension is the force that holds droplets together, preventing them from breaking apart easily. However, when a droplet reaches a critical size, air resistance becomes greater than this force, causing the droplet to split.
This explains why rain is made up of countless tiny drops, rather than a single giant drop falling from the sky.
How raindrops fall
The falling of raindrops is not a random process. When a drop begins to descend, it creates an air path in its path, facilitating the descent of other drops right behind it.
This phenomenon is similar to the trail left by boats in the water, where the movement creates a wake that influences the flow around it.
Furthermore, the speed at which raindrops fall depends on their size. Smaller drops fall more slowly and can be suspended in the air by updrafts, while larger drops fall more quickly.
As they fall, some drops merge with others, increasing in size, while others split due to impact with the air.
Another interesting fact is that raindrops do not always fall in a straight line. Strong winds and air currents can cause them to follow inclined or even upward trajectories before finally hitting the ground.
Electricity and the union of drops
Research indicates that atmospheric electricity can influence the formation and behavior of raindrops.
When two electrically charged droplets meet, the attraction between opposite charges can facilitate their fusion. This factor may explain why some droplets stick together while others break apart along the way.
The importance of rain for the planet
Rain plays an essential role in sustaining life on Earth. It supplies rivers and lakes, irrigates crops and regulates the planet's temperature. It also helps clean the atmosphere by removing pollutants and particles suspended in the air.
With climate change, rainfall patterns are shifting, affecting ecosystems and communities around the world.
The increase in extreme weather events, such as intense storms and prolonged droughts, requires a greater understanding of the behavior of the atmosphere and human influences on the climate.
With information from scienceabc.
