Answer:
Hiii how are you <u>doing?</u><u>?</u><u>I </u><u>don't</u><u> </u><u>understand</u><u> </u><u>that</u>
The sphere slow down due to friction force between the surface of the sphere and the surface on that the sphere is rolling . The friction force acting against the motion of the sphere. Thats why it is slowed down. In fact not only a sphere, anything can not slow down untill a force act against it's motion.
The sinking of cold air creates regions of high pressure and this air travels to lower pressure regions produced by the rising motion of warm air. This process results in air circulation.