Weather balloons are released at the same time around the world at every launching site. The date received from the balloons are sent to a central computer in Maryland. To send the balloons, they are inflated with either helium or hydrogen. As the atmospheric pressure decreases, the gas inside expands the balloon. They have been used since World War II. The instrument in the balloon transmits barometric, relative humidity, and temperature date to the ground by radio transmission using a multiplexing system.

1. They did not become obsolete because they gather information in different ways than most things.

2. They would have to understand gas laws because the balloon has gas in it to make it fly. Also the atmosphere has different gases in it that the meteorologist has to understand for it to work properly.

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