Have you ever wondered that even though it rains down but why the clouds do not fall 🌨? This thought often bothered me during rainy days in my childhood.
But one day, when I was reading a book 📖 ‘ That’s Maths The Mathematical Magic in Everyday Life’ by ‘ Peter Lynch’, I came across the same question so I got involved quickly reading it further. Afterall, it had been my long-time curiosity.
It stated that it was George Gabriel Stokes, a great mathematician and physicist who explained this concept.
Clouds are formed of small and large droplets. He investigated that small droplets are suspended in the air due to internal friction of fluids.
Actually, there are two forces acting on droplets- gravitational force and drag force by air. The drag force needed to move the particle through a viscous medium is given by Stokes law
F = 6 π η R v
η is viscosity
R is radius of sphere
v is velocity
Drag force acts due to the warm air rising from surface of earth by heat of the sun.
In case of small droplets, the drag force of air dominates over gravitational force whereas for large droplets, the gravitational force dominates over drag force of air.
Hence large droplets fall as rain whereas small droplets are suspended in the air in the form of clouds.