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What happens inside a cloud?
Micro-scale Processes - Rain Droplet Formation
Once cloud droplets become heavy enough, they can fall out of the cloud as rain. But they have to reach a certain size because clouds are characterized by updrafts, which keep small, light droplets suspended in air. A typical raindrop is 100 times larger than a typical cloud droplet. Through condensation alone, it would be very difficult for a cloud droplet to grow large enough to fall as rain.
Luckily there are other processes that form raindrops, such as
collision and coalescence.
This process forms raindrops in clouds with above-freezing temperatures at all
levels ("warm clouds"), or in the warmer regions of cold clouds.
The most important factor in the production of raindrops is the cloud's liquid water content. The more droplets there are, the more likely falling droplets will encounter them and grow through coalescence.
It is also important that a range of sizes of droplets exists. It is necessary to have some large droplets that will fall and a range of smaller droplets that do not fall or fall more slowly, so the large droplets can collide with them.
Next page -> Micro-scale processes - rain droplet formation continued
Links and resources
Micro-scale Processes - Rain Droplet Formation
Once cloud droplets become heavy enough, they can fall out of the cloud as rain. But they have to reach a certain size because clouds are characterized by updrafts, which keep small, light droplets suspended in air. A typical raindrop is 100 times larger than a typical cloud droplet. Through condensation alone, it would be very difficult for a cloud droplet to grow large enough to fall as rain.
Luckily there are other processes that form raindrops, such as
collision and coalescence.
This process forms raindrops in clouds with above-freezing temperatures at all
levels ("warm clouds"), or in the warmer regions of cold clouds.The most important factor in the production of raindrops is the cloud's liquid water content. The more droplets there are, the more likely falling droplets will encounter them and grow through coalescence.
It is also important that a range of sizes of droplets exists. It is necessary to have some large droplets that will fall and a range of smaller droplets that do not fall or fall more slowly, so the large droplets can collide with them.
Next page -> Micro-scale processes - rain droplet formation continued
Links and resources
