Ballon

METEOROLOGICAL BALLOONS

Twice a day of the year, weather balloons are released simultaneously from almost 900 locations worldwide! This includes 92 released by the national weather service in the US and its territories. The balloon flights last for around 2 hours, can drift as far as 125 miles away, and rise up to over 100,000 ft. (about 20 miles) in the atmosphere!

Weather balloons, which are made of latex or synthetic rubber (neoprene), are filled with either hydrogen or helium.

STABILIZED BALLOONS

Wind vertical profile measurement: Wind vertical profile accuracy must be measured on the whole means used, i.e., that is necessary to take account of sonde accuracy, receiver accuracy and balloon performance as well. Jim spheres, Rubsondes, Cap spheres and Méduse can resolve scales around 200m. They are "good wind followers" balloons.

How to stabilize a balloon: Note : Don't confuse balloon stabilization with wind following. Balloon stabilization reduces the sonde pendulum and consequently GPS measurement pollution, but it doesn't improve wind measurement at all. To make the balloon more stable, a solution consists in increasing the roughness of the balloon surface. Thus the size of the drag is increased, which cause to increase the trail and decrease the lift. These balloons are thus designed to avoid random boundary layer detachment and to absorb the turbulent energy of the wake. It is necessary to associate a true 3D GPS because it give a three-dimensional localization and Doppler velocity measurements more accurate than those obtained by deriving the position.

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