Amateur radio high-altitude ballooning

Amateur radio high-altitude ballooning is when people use weather balloons to float a box containing equipment (called a payload) high up into the sky to study things like the atmosphere and take pictures. A weather balloon is a large balloon filled with helium gas which is much lighter than air, so it can lift the payload up into the atmosphere. Amateur radio is also used to send signals from the payload to the person who launched it, so they can track where the payload is and get information about what it's seeing and doing.