1. Made by Vika Kudoyarova

2. A b o u t b a l l o o n i n g Balloon is bag filled heated air or a light gas so that it rises and floats in the air. A balloon rises because the heated air or gas inside is lighter and less dense than the surrounding air. Balloons may be captive, free – floating or powered. A captive balloon is anchored to the ground by a cable. A free – floating balloon travels in whatever direction the wind blows. A pilot can control the vertical movement of a manned, free – floating balloon but cannot steer it. However, the pilot can control the course of balloon light to some degree by rising or descending to find a wind blowing in the desired direction. A powered balloon is called airship. An airship has an engine and propellers to power it, along with rudders and instruments.

3. Kinds of balloons There are two chief kinds of balloons: hot - air balloons and gas balloons. Hot – air balloons are used mainly for sport ballooning. Gas balloons are used for sport ballooning, scientific research, and a variety of other purposes.

4. Hot – air balloons Hot – air balloons rise because the air inside the bag is warmer – and therefore lighter – than the surrounding air. Air expands when heated, which makes it lighter than an equal volume of cool air. The heat for a hot – air balloon comes from a burner produces a flame that reaches up into the bag. The bag is a hot – air balloon is made of nylon or polyester. The size of the bag depends on the weight of the payload that the bag has to lift. The payload consists of the basket, passengers, equipment, and supplies.

5. Gas balloons Gas balloons may be inflated with hydrogen, helium, or natural gas. Hydrogen is the lightest of all gases and so has the greatest lifting power. But hydrogen must be handled with care because highly combustible. Although helium is slightly heavier than hydrogen, it is much safer. Natural gas produces less lift than either hydrogen or helium but costs far less.

6. History In the late 1700s, two French papermakers, the brothers Jacques Etienne and Joseph Michel Montgolfier, began experimenting with hot – air balloons. The Montgolfiers started their experiments by filling small paper bags with smoke. They at first through the smoke made the bags ascend. But they latter learned the hot air caused the bags to rise. On June 7, 1783, the brothers sent up a large small filled balloon at a public gathering in Annonay, France. The balloon was made of cloth lined and measured 35 feet (11 meters) in diameter. Three month later, they launched a balloon that carried a duck, a rooster, and a sheep. The flight lasted about eight minutes, and the animals landed safely.

7. How balloons are used Scientific uses. Expandable balloons are widely used by meteorologists (scientists who study the weather). These balloons often carry an instrument called a radiosonde. A radiosonde has meters that measure the temperature, humidity, and pressure of the air at various altitudes. It also includes a radio, which sends the readings to stations on the ground. Meteorologists use this information in forecasting the weather.

8. How balloons are used Recreational uses. Gas and hot- air balloons are both used for sport ballooning. Many balloonists participate in races and rallies. Others simply like to drift peacefully over the countryside.

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