I was wondering what exactly triggers clouds to rain and how heavy the rain is. I live in a mountain region, so i heart the terms of clouds being too heavy and low, so they get stuck and rain off. But that doesn’t feel to be entirely true and more of a folks tale.
So how does it happen?
In: Physics
Clouds are masses of condensed droplets of liquid water (or deposited crystals of solid ice, or condensed and then frozen solid ice) falling through air that’s simultaneously rising (powered in part by the latent heat of water vapour being released as it condenses).
The speed at which these droplets fall at is determined by their mass and drag, which in turn is roughly proportional to their volume and surface area. As they grow larger from more water condensing/depositing on them, their volume grows *much* faster than their surface area (an effect known as the square-cube law).
When the mass of a drop is too large for its drag and the vertical winds within/below a cloud to hold up, it falls as rain (or other precipitation). Under some conditions it can evaporate before hitting the ground.
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