Convective zone

A zone in a star where energy is mostly transferred through convection. The convective zone is the outer-most layer of the solar interior. In a typical main sequence star, it reaches a depth of about 150 000 km. The temperatures are low enough (around 1 million degrees K) for the atoms to hold on to their electrons. This makes the atoms excited and they bounce around at high speeds.

At the surface you can see this convection as the granules. As this gas gets hotter it expands, which makes it move towards the surface. When it reaches the surface it cools down and sinks again. Energy is transported much faster in this region than in the radiative zone. The convection zone is sometimes called the "Boiling zone".