Clouds and Winds: How Clouds Spin, Merge, and Make Rain
Notes on the behaviour of clouds driven by winds, with small pen sketches of clouds and rain
Under the heading 'Wind', these notes analyse how clouds behave when struck and driven by winds. A wind hitting one side of a cloud spins it into a compound rotating motion, like a mill wheel turned by water; contrary winds drive two clouds together so they merge and rise where their passage is least hindered; and clouds overtaking one another on the same wind condense at their contact and make rain. Small pen sketches of a rain shower and cloud masses accompany the text at the right.
On this page
Wind spins a cloud like a mill-wheel
A wind striking one side of a cloud, even while the opposite side hangs motionless, drives the cloud forward and turns it, producing a compound rotating motion likened to a mill wheel turned by water. The note also asks what cause makes clouds grow so high.
Contrary winds drive two clouds together
When two contrary winds bring two clouds to collide, the clouds merge into one another. Unable to spread out or sink because the wind passes beneath them, they extend upward, where their passage is least obstructed.
Clouds overtaking each other make rain
When a single wind makes two clouds overtake one another, the larger (having the stronger share of wind) 'clothes' the smaller. At their common contact they condense one another, and rain is produced.