Have you seen cloud moving across the sky?

    Have you seen cloud moving across the sky?

They are blown by the wind.

Wind is moving air wind blows in differnent directions and at different speeds

. + lot air is lighter than cold air.

This is why smoke always rises.

This is reason. 

Why not air balloons can rise high in the sky.

                   Write by Sheraz Dilpul from C.E.L.C