Why Does Rain Fall In Drops And Not All At Once?

How does rain begin?

When clouds gather bit by bit and rain is just around the corner, it’s a sign that many meteorological processes are culminating . First, water needs to enter the atmosphere. It evaporates from lakes, rivers, and the oceans. In addition to water bodies, vegetation in biomes like grasslands and forests are also important sources of water. Once water vapor rises into the atmosphere, it undergoes a sudden change in temperature. The air gets cooler and cooler the higher up you go. The drop in temperature changes water vapor (gaseous water) into droplets (liquid water). The droplets come together and make clouds.

In clouds, water droplets get even colder and solidify into ice crystals. Clouds appear white because the tiny crystals of ice scatter light in all directions! Once the clouds accumulate enough ice, they need to reach a critical size before the rain can begin.

Clouds hold their structure and form wonderful shapes because of air resistance . Air resistance is a force that the atmosphere exerts on all objects within it. Although the atmosphere looks like nothing and is difficult to perceive, it’s made up of millions of air molecules. When an object moves through the atmosphere, it has to navigate through this invisible maze of air molecules. It tends to bump into them, creating friction and resistance. Characteristics of the object, like its material, size, shape, and speed, all affect the air resistance.

Clouds are pushed into their forms by air resistance. When a cloud gains enough mass, the weight of the ice crystals overcomes the pushing force of the air resistance. The cloud then breaks apart and turns into a cluster of ice crystals. As the crystals fall down towards the Earth, they warm up and turn back into water. After all of this happens, the rain finally begins.

Why does rain fall drop by drop?

The first reason that rain falls by drop and not all at once is that rain was never one piece or unit to begin with! Although clouds can look like extensive sheets or like one big tuft, each cloud is made up of millions of pieces of ice. Since the individual crystals are what make up rain, and not the cloud as a whole, each tiny crystal turns into the beginnings of a raindrop.

Raindrops are also shaped by air resistance just as much as clouds are! Tiny and light raindrops aren’t affected much by air resistance, and so they fall in almost perfect spheres. As raindrops fall downwards, the air resistance is higher on the bottom of the droplet. Larger raindrops get squashed due to this friction. The sides of raindrops also encounter more resistance than the middle of the drop, as they encounter air on multiple sides. This means that either side of a very heavy raindrop gets more air resistance than its middle. Eventually, the largest rain drops split into smaller ones.

Rain could never fall as a big sheet, as the sheet wouldn’t be able to hold together. Air resistance splits it into smaller and smaller sections. These sections are also shaped by air resistance, forming the squashed blobs that look like the teardrops we picture.

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