Thermal airship

A thermal airship is a type of airship (a vehicle that flies through the air like a balloon or blimp) that uses a different type of lift to fly than a normal airship. Instead of using hot air or helium like most airships, a thermal airship uses rising air currents called thermals. Thermals are created when the sun heats up the ground and the air around it. The warm air rises, like when you blow up a balloon. The thermal airship can take advantage of this rise by filling its large balloon with cold air. The warm air that is rising will lift the balloon and make it fly, like the hot air balloon. This way the thermal airship can stay up in the sky much longer than a hot air balloon because it doesn't have to carry any hot air with it.