What does air carry?

Even though we cannot see air, it is not just empty space, Air that surrounds us all the time is mainly a mixture of many gases. Air exerts pressure on us, but still does not crush us. In principle, we are living on the floor of a kilometer- thick ocean of air knows as the air cover or the atmosphere of  the Earth. Since, air is matter, it can also carry things: leaves in autumn, birds, aircrafts, hot-air balloons, and many more things. However, all objects need propulsion to lift from the ground - birds beat their wings, aircraft depends on propellers or jet engines.

How do aircrafts fly?

Aircrafts need a combination of procedure to fly in the air. They need a propulsion system- a propeller or a jet engine. They also need a lift, which comes from their wings. While flying, the forward thrust causes the air to flow at great speeds along the wings. The curved shape of the wings and their slightly tilted position give rise to a low pressure above the aircraft and high pressure below it. This is how the aircraft is pushed upwards. This is how the aircraft is pushed upwards. The pressure difference thus generates a buoyancy  which is greater then the weight of the aircraft, which of the aircraft, which pulls it down. The aircraft will fall if the buoyancy is less

How does a hot-air balloon float in air?

Air at a temperature of around 90 C is filled into the hot-air balloon. The hot air keeps the balloon in the air because its density is lower than that of the surrounding cold air. Before starting the balloon, a gas burner is ignited below  the opening of the huge balloon cover and the flame heats up the air in the balloon. When the balloon rises to the desired height, the burner is switched off; if one wants to rise further, it is started again. The balloon must have a minimum size so that it can overcome the force of gravitational attraction of  the Earth. Thus, hot air balloons are able to float in air and look so beautiful in the sky.