What causes raindrops to be different sizes?
Raindrop size varies with many factors-including moisture content, lifting motion, and turbulence within a cloud. As cloud droplets (with a diameter similar to that of a human hair) are jostled or 'bang around' within a cloud because of lifting and turbulence, some stick to each other, growing larger. The taller the cloud (such as huge cumulo-nimbus clouds) the bigger the rain drops because of all the turbulence within it. When hail melts, the remnant water drops can be very big!