As the water gets hotter, bubbles start to rise from the bottom of the pot. As the water begins to boil, the surface bubbles get more numerous and rolls form. This process is called convection. Earth's surface receives the radiation from the Sun and heats up. The heat is transferred to the air by conduction between the surface and the first few centimetres of air.
Convection brings the heat up from the surface into the lower atmosphere.
You have seen convection occur over your heads, but probably didn't realize it. This situation is just like the bubbles in a pot of boiling water, where the rising bubbles are like the clouds. The Space Shuttle is launched from Florida, where thunderstorms are common. The lightning can harm the electronic devices on the Shuttle. This electricity is generated by the solar wind.