How does height of a parachute affect air resistance compared to circumference or diameter? I'm trying to find out how much a double in height (making it more ovular or oblong in shape) of the parachute affects air resistance compared to a double in circumference or diameter. Can someone tell me if parachutes with the same circumference (therefore looking the same when looked from the top) but are taller or shorter have different air resistance?
 A: Air resistance or air drag is basically proportional to square of the velocity of the moving    object ,that is, F=bv^2 since air has turbulent motion where b is the air drag constant.Drag constant depends on the dimensions of the object. So air drag is independent of length or volume of object, rather it depends on the surface area of the object.
The action of the parachute is based on the principle of air resistance. It dramatically lowers your terminal velocity by increasing your air resistance as you fall. It does that by opening out behind you and creating a large surface area of material with a huge amount of drag. Parachutes are designed to reduce your terminal velocity by about 90 percent so you hit the ground at a relatively low speed of maybe 5–6 meters per second (roughly 20 km/h or 12 mph)—ideally, so you can land on your feet and walk away unharmed.
Increasing the height of the parachute hence does not affect air resistance.
But increasing the circumference of the parachute in turn increases the surface area of the parachute and it increases the air drag exerted on the parachute.
Similarly for parachutes with same circumference, air resistance is same.
