During convection, cool and dense air falls through the warmer and less dense air. The warm air having less mass is being displaced by the cooler which is much heavy. Convection always involves the air rising through the atmosphere.
The ball with which Table Tennis is played is called Ping Pong Ball.
According to the International rules, the diameter of the ping pong ballmust be not less than 39.5 millimeters and not greater than 40.5 millimeters having a mass of 2.7 grams.