Answer the following question given this paragraph: 

Weather stations contain many instruments for measuring weather conditions. The weather balloon ( Figure above ) will rise into the atmosphere until it bursts. As it rises, it will gather weather data and send it to the surface. Many weather satellites orbit Earth. They constantly collect and transmit weather data from high above the surface. A radar device sends out radio waves in all directions. The waves bounce off water in the atmosphere and then return to the sender. The radar data shows where precipitation is falling. It’s raining in the orange-shaded area shown above.


Q: When do weather balloons return to earth?


A:
when it bursts