How do glider use convection to stay flying?

Convection allows warmer air to rise because it is less dense than colder air. Because temperatures are greater near the ground (due to the ground's absorption of infrared radiation from the sun), the air at ground level tends to be warmer than the air at higher altitudes. Therefore, the air at ground level rises to form convection currents (currents of rising air), which, when impacting a glider's wings, generates lift, which allows them to remain in the air, or even rise to higher altitudes.