Did you know that Hailstones can travel at 90km/h?

     In the summer of 1984 the inhabitants of Munich discovered just how dangerous hail can be. After a relatively cool start to the season, the city became very hot within just a few days. The temperature climbed to 37C, but only a few days later a cold front moved across Germany, with catastrophic consequences. Hailstones the size of tennis balls beat down on Munich, causing damage worth over 1.5 billion Euros.

                     Speed                     Size
             
     Hailstones      25m/s  (90km/h)           up to 100mm
   
     Rain drops      8m/s   (29km/h)           0.6-3mm

     Snowflakes     0.8m/s (2.88km/h)         5-30mm


Huge hailstones like these occur when hot, humid air collides with cooler layers of cloud, causing unusually strong updraughts.