More About Raindrops

Cloud droplets are so small that you need a magnifying glass to see them.

Most people think that
raindrops look like tear drops.
Like the one below.

This is not true. They are round like me or a little flatter like 'Megadrop'.

Here are a few of my raindrop mates! ...

This is 'Megadrop'.
It is a large raindrop.
It is 5 millimetres in size.

As it falls from the sky it flattens out.

This is 'Dropoid'.
It is a small raindrop.
It is only 1 millimetre in size.

More About Raindrops

How are raindrops made? First you need a small particle on which water vapour will collect (condense). These small particles may be specks of dust or even tiny living things like bacteria.

We call this particle a 'condensation nucleus' (con - den - say - shun) (new - clee - us).

As the particle collects more water vapour it grows bigger. The winds in the clouds blow the droplet around. It hits other drops and joins up with them, making bigger drops.

Perhaps you are wondering why rain falls from some clouds and not from others. The answer lies in the size of the cloud droplets and the raindrops.

The diameter of a typical cloud droplet is 0.01 to 0.02 mm whereas a typical raindrop has a diameter of 1 to 2 mm and large raindrops from thunderstorms may have diameters of 5 to 8 mm.

The tiny cloud droplets float in the air, borne aloft by the winds in the cloud, but the larger raindrops are able to overcome the winds and fall to the ground.

All bodies fall towards the earth under the influence of gravity and meet with resistance from the air. Their speed increases as they fall until the air resistance balances the pull of gravity.

Tiny cloud droplets are so small that they are kept aloft and often swept up into the cloud by the rising air within the cloud.

Drizzle drops (diameters 0.2 to 0.5 mm) will be able to fall slowly to the ground if the rising air is too gentle.

Sometimes raindrops evaporate as they fall towards the ground and appear as thin streamers coming from the cloud base - this is called 'virga'.

The strong winds in large convective or thunderstorm clouds can keep very large drops aloft and sweep them up into the upper parts of the cloud. The drops can fall to the ground when they move out of the strong winds and in some cases they are brought to earth at high speed under the influence of strong winds blowing down to earth.

Larger raindrops take on a shape more like a plum pudding than a teardrop as they fall. The drop is flattened at the bottom because the air pressure is greater on the bottom than it is on the sides.

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