Friction is the resistance force that appears when two bodies or substances are rubbed together. It slows things down and opposes motion. Without friction, people would not be able to walk, run, write or play sports. Things would continue to move unless they hit anything in their way. Static friction also holds screws and nails in wood and without it, the parts wouldn't hold together.
Cars would not stop moving without friction. The force of friction in a vehicle's moving parts, however, would also prevent it from working properly. For example, too much friction would prevent engine parts from sliding past each other and would even cause overheating. With very little friction in these parts, the engine works more efficiently and parts don't wear out as easily.
Although friction in mechanical parts can cause problems, friction is an important force. Without it, the speed of the wind would not decrease or change direction.
The effect of friction, however, is more relevant on the surface of the Earth. The wind is stronger higher up in the atmosphere, where fewer obstructions slow it down. The lack of friction in the higher part of the atmosphere is what causes hurricanes and tornadoes to have higher and gustier upper level winds.