The horse latitudes are the areas in the northern and southern hemispheres of the Earth, lying between the two big wind zones: between the trade wind and the westerly wind areas. In these areas, there is almost always no wind. Therefore, the sailboats of the early sailors were stalled often for weeks. The region of the subtropical high was given the name ‘horse latitudes’ because the sailors who transported horses on their sailboats threw their horses and cattle overboard to save on provisions during the long periods of calm. The areas were reported to be ‘strewn with bodies of horses’. This is supposed to be one of the reasons why these areas came to be known as horse latitudes.
Wind creates special shapes in nature. These include the elongated dunes of the sandy deserts, which are always reshaped by the wind and the treetops, which adapt their appearance to the constantly blowing wind. With its constant force the wind also erodes the surface of the rocks and hollows them out gradually. This is known as wind erosion. This gives rise to rocky arches, troughs, and spires. Wind erosion also takes place in the unprotected fields, where the fertile soil cover is blown away. In this way, the wind contributes to the spread of deserts in the dry regions of the Earth.
Aircrafts need a combination of procedures 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 and their slightly titled position give rise to a low pressure above the aircraft and high pressure below it. This is how the aircraft is pushed upwards. The pressure difference thus generates buoyancy, which is greater than the weight of the aircraft, which pulls it down. The aircraft will fall if the buoyancy is less.
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. 
A propeller in an aircraft scoops air, just like it scoops water in a ship. As in a wind mill, the blades of a propeller are arranged in the form of a star around a rotating shaft. They are shaped and aligned in such a way that the air falls diagonally on them and flows along them. This creates a strong air flow that gives the aircraft the required thrust. This principle is used not just by the smaller aircrafts but also by hovercrafts, which can travel over meadows or frozen water. 
The sun is the source of all energy either in the form of fossil fuels or wood. After all, these substances have been made from the energy of the sun and have stored its energy. However, the heat of the sun can be used directly in the form of solar energy. Solar cells and giant solar plants are used for generating electricity. It has been estimated that the solar energy reaching the Earth’s surface in one year is double than we will ever receive from all the Earth’s resources of coal, oil, natural gas, and uranium together.