India

A hot air balloon is a lighter-than-air aircraft consisting of a bag, called an envelope, which contains heated air. Suspended beneath is a gondola or wicker basket (in some long-distance or high-altitude balloons, a capsule), which carries passengers and a source of heat, in most cases an open flame caused by burning liquid propane. The heated air inside the envelope makes it buoyant since it has a lower density than the colder air outside the envelope. As with all aircraft, hot air balloons cannot fly beyond the atmosphere. Unlike gas balloons, the envelope does not have to be sealed at the bottom, since the air near the bottom of the envelope is at the same pressure as the surrounding air.

In modern sport balloons the envelope is generally made from nylon fabric and the inlet of the balloon (closest to the burner flame) is made from a fire resistant material such as Nomex. Modern balloons have been made in all kinds of shapes, such as rocket ships and the shapes of various commercial products, though the traditional shape is used for most non-commercial, and many commercial, applications.

Scuba diving is a mode of underwater diving where the diver uses a self-contained underwater breathing apparatus (scuba) which is completely independent of surface supply, to breathe underwater.Scuba divers carry their own source of breathing gas, usually compressed air, allowing them greater independence and freedom of movement than surface-supplied divers, and longer underwater endurance than breath-hold divers. Open circuit scuba systems discharge the breathing gas into the environment as it is exhaled, and consist of one or more diving cylinders containing breathing gas at high pressure which is supplied to the diver through a regulator.

They may include additional cylinders for range extension, decompression gas or emergency breathing gas. Closed-circuit or semi-closed circuit rebreather scuba systems allow recycling of exhaled gases. The volume of gas used is reduced compared to that of open circuit, so a smaller cylinder or cylinders may be used for an equivalent dive duration. Rebreathers extend the time spent underwater compared to open circuit for the same gas consumption; they produce fewer bubbles and less noise than open circuit scuba which makes them attractive to covert military divers to avoid detection, scientific divers to avoid disturbing marine animals, and media divers to avoid bubble interference.

Tourism is travel for pleasure or business; also the theory and practice of touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tours. Tourism may be international, or within the traveller’s country. The World Tourism Organization defines tourism more generally, in terms which go “beyond the common perception of tourism as being limited to holiday activity only”, as people “traveling to and staying in places outside their usual environment for not more than one consecutive year for leisure, business and other purposes”.

Dedicated road bicycles have drop handlebars and multiple gears, although there are single and fixed gear varieties. Road bikes also use narrow, high-pressure tires to decrease rolling resistance, and tend to be somewhat lighter than other types of bicycle. The drop handlebars are often positioned lower than the saddle in order to put the rider in a more aerodynamic position. In an effort to become more aerodynamic, some riders have begun using aerobars.

And when aerobars where invented is unclear but they seem to date back to the early 1980s. The light weight and aerodynamics of a road bike allows this type of bicycle to be the second most efficient self-powered means of transportation, behind only recumbent bicycles due to the latter’s higher aerodynamic efficiency.

Mountain bikes fitted with slick or semi-slick are also popular for commuters. Though less efficient, the upright riding position allows the cyclist a better view of traffic, and they can also be readily fitted with mudguards, cargo racks and other accessories. Mountain bikes are usually ridden on unpaved roads and tracks but they are not to be confused with cyclocross bikes.