Ceiling balloon

A pilot balloon is used by meteorologists to determine the height of the bottom of the clouds above the ground during daylight hours. The balloon is to fill such a manner that its rising speed is known. From the measured time interval between the start of the balloon and its immersion in the cloud can be so close to the height of cloud base. By tracking the trajectory, formerly with a theodolite, today by radar or GPS, direction and speed can be determined by high-altitude winds.

History

The pilot balloon in its present form was introduced in 1901 by Richard Assmann in Berlin. In contrast to the balloon fabric, gold-beater skin or paper previously used rubber balloons secured a consistent and previously known ascent rate.

Handling

A pilot balloon is a small, usually red rubber balloon, which measures 76 mm in general before filling. The balloon and the relative equipment are typically housed in a cabinet which is attached to a wall close to the gas cylinders. The cabinet has three doors, one of which opens downward and to which the filler stand is attached. At the top of the filler, an "L " -shaped tube is mounted on the stand with two rings, a little on the bottom, and a larger on the upper side of the filling nozzle. Prevent Rings, can make sure the end the stand fall or rise too far, when the balloon is inflated. The upper ring has been incorporated some of the grooves that will help him to access the balloon, which is attached to it.

At the bottom of the tube is a weight which, when the exact amount of gas has been filled, raises, indicating that the balloon is full. A rubber hose is attached to this tube and thereby exceeds the filler stand twice. The first hole is larger than the tube to permit movement of the tube, while the second is used to hold the tubes in position. The tube passes to a needle valve, which controls the amount of gas flow to the balloon. A second tube then passes from the valve to a control valve which is mounted on the gas cylinder. This valve has two mounted pressure gauge. One which. The total pressure in the gas cylinder and a second view showing the amount of gas flowing through the tube Usually, the cylinder of steel and weighs approximately 63.5 kg. It provides nearly 5.7 cubic meters of gas with a pressure of 14 MPa and can inflate about 120 balloons. On the opposite side of the cabinet, the space for storage of the balloon. As the filling gas usually helium is used, but it can also be hydrogen.

The balloon is brought to the gas nozzle and a piece of tape is wound around the neck of the balloon. After the placing of the goggles and the hearing protector, it is checked whether the needle valve is completely closed. The main valve on the cylinder is opened, it follows the opening of the regulator valve. First, the needle valve is opened and the balloon begins to fill itself. When the balloon reaches the correct size, the filling nozzle begins to lift. At this point, the needle valve is closed with the control valve and the cylinder valve. The adhesive tape is then used to tie the baloon, so that no gas can escape.

After the filling of the balloon has been made out, it is released. The time from the start until the cloud cover is measured. When it is properly inflated, the balloon is increasing at a rate of 140 meters per minute (460 ft / min). The bottoms of the clouds are very rarely flat and firm, so that the height of the clouds is achieved when the color of the balloon begins to fade and not when it disappears. The balloon can also be used to measure the vertical view in a blanket of fog. In this case, the balloon begins to fade when it is released, so that the vertical run, disappears when the balloon. When the balloon for a considerable period in the cloud layer is visible, it should make a note of the observer, because this is a value for the density of the clouds.

The pilot balloon is to get a reliable, safe and easy means of data on the height of the clouds. However, it has some drawbacks that need to be aware of the observer. Rain and wet snow can slow the rise of the balloon, which result in a false reading for the cloud ceiling height and in poor visibility can disappear the balloon before it reaches the cloud. When the balloon ( 460 ft / min ) at a rate of 140 m per minute increases, it takes five minutes, until the balloon reaches 700 m (2300 ft). About this height also to follow the balloon, for example, a pair of binoculars is difficult because even a slight movement of the eye away from the balloon leads that you lose visual contact.

At night, it is not practical to use a balloon. Then the clouds projector is being used. However, during the dusk it may be impossible to use the cloud projector and then an illuminated trial balloon to be used. This provides a simple flashlight bulb which is attached to a battery. To charge the battery, it is immersed in water for three minutes, and then bonded to the balloon prior to inflation. These are now used rarely. Caution must be used during inflation because of the occasional faulty balloon and its default. If the person inflating the balloon, neither goggles still wearing hearing protection, eye or ear damage can occur in the case of burst.