Adam+Aschenbrenner+Weather+Balloons

Every 12 hours a hydrogen or helium packed balloon is launched at 70 different places around the United States. These balloons help make the weather forecasts. These have been used since World War II. All 700 release sites around the owrld release the balloons at the same time. The info goes to a computer in Maryland and that sends out the info to places all over the country. The balloons have a diameter of about 2 meters when they are full. An instrument package is connected to the the balloon by a 15 meter cord. When the weather balloon reaches a height of 30km, the volume of the gas causes the balloon to burst. A parachute then carries the package that contains the radio transmitter and measuring instruments to the ground. The devices in the instrument box record temeperature, relative humidity, and barometric pressure. Humiddity reading are obtained from a device that gets bigger when it becomes moist. Wind velocity is found by tracking the balloon on a radar or by a radio location system. The system transmits the data in a rotation, for example, temperature first, followed by humidity, and then pressure.