WindAir in motion is called wind.How wind is caused:Wind is caused by difference’s in atmospheric pressure.Instrument for measuring of wind velocityCup anemometer: (https://www.google.com.pk/url?sa=i=j==s=images==0ahUKEwjc1L_m8OXYAhVLC-wKHWxHBpYQjxwIAw)Vane anemometer: (http://www.directindustry.com/industrial-manufacturer/wind-vane-anemometer-161086.html)Instrument for measuring of wind direction:Weather vanes:Weather vanes are one of the oldest of all weather instruments, working by swinging around the wind to show which direction it is blowing from. The head of the cockerel would point into the wind, indicating the direction the wind was blowing from. (http://www.ebay.com/gds/How-to-Install-a-Weathervane-/10000000178630524/g.html)wind socks:Another device is wind sock. This instrument is found mainly at airports ,seaports and other open areas where a very visual indication of the wind is needed. This information is very useful to people on both ships and planes. (http://airportwindsocks.com/windsocks-c-13/white-aviation-windsocks-c-13_45/)Anemometer:An anemometer looks like weather vane, but instead of measuring which direction the wind is blowing with pointers, it has four cups so that it can more accurately measure wind speed. (https://www.quora.com/What-is-the-difference-between-a-wind-vane-and-a-anemometer-What-are-some-examples)(4): Why is measuring wind speed so important:The amount of electricity a wind turbine can generate depends on the local wind speed.There are many situations where measurment and knowledge of the wind condition helps in decision making such as pollution control, safety of tall structures ,control of wind turbines.