Security threat or hot air? A guide to high altitude balloons.

Every day, hundreds of tiny balloons help with weather forecasting, says Jesse Geffen, a manager at Kaymont Consolidated, which supplies weather balloons to the US government.

Measuring about six feet in diameter, costing about $40, these balloons are usually filled with helium or hydrogen and rise at a speed of about 300 feet per minute. A small sensor measures temperature, humidity, wind speed and direction and shoots the readings to National Weather Service stations in real time, Geffen said.

As the balloon rises, the pressure inside steadily increases. Once it reaches about 90,000 feet, the balloon reaches its limit and bursts into thousands of tiny biodegradable plastic pieces, Geffen added. This self-destruct minimizes their impact on the environment.