(i) In summer, the average kinetic energy of the air molecules inside the tyre increases due to high temperature i.e. the molecules move fast due to which the pressure on the walls of the tube increases. If pressure inside is not kept low at the time of inflation, at high temperature, the pressure may become so high that the tyre may burst.
(ii) The atmospheric pressure decreases on moving to higher altitudes. So, the pressure outside the balloon decreases. To regain equilibrium with the external pressure, the gas inside expands to decrease its pressure. Thus, the size of weather balloon becomes larger and larger as it moves into higher altitudes.
