Wind resistance is overall drag on a body due to its interaction with the atmosphere. The term is actually quite vague, and is often applied to a number of different types of drag, but since the overall effect is often most important, the term is widely used. For a solid object moving through a fluid or gas, drag is the sum of all the aerodynamic or hydrodynamic forces in the direction of the external fluid flow. ... Layers of Atmosphere (NOAA) Earths atmosphere is the layer of gases surrounding the planet Earth and retained by the Earths gravity. ...

The power required to overcome drag due to any fluid varies with the cube of velocity, meaning that it grows rapidly with increasing speed. This is why a car may need only 25 horsepower (20 kW) in order to cruise at highway speeds, while requiring perhaps 200 horsepower (160 kW), eight times as much, to travel twice that fast. The effect is even more pronounced in aircraft, where efforts to reduce the drag coefficient become vitally important, as increasing engine power also increases the weight of the aircraft and thus the induced drag. A subset of the phases of matter, fluids include liquids, gases, plasmas and, to some extent, plastic solids. ... Velocity (symbol: v) is a vector measurement of the rate and direction of motion. ... A small variety of cars, the most popular kind of automobile. ... The horsepower (hp) is the name of several non-metric units of power. ... An aircraft is any machine capable of atmospheric flight. ... The drag coefficient (Cd or Cx) is a number that describes a characteristic amount of aerodynamic drag caused by fluid flow, used in the drag equation. ...