So wind is caused by pressure systems. What creates these?

Answer 1

Areas of low pressure form when a mass of air warms up. This can happen because the airmass passes over a warm surface such as land or oceans or due to the condensation of water vapour. As the air warms it expands, mostly in an upwards direction, the air also becomes slightly denser.

The upward expansion into the troposphere results in some of the air mass being carried away thus reducing the mass (weight) which causes low pressure.

Air from the surrounding areas of high pressure then move to fill the partial vacuum caused by the low pressure, the greater the difference between high and low pressure the stronger the winds. The rotation of the Earth causes the wind to blow in a counter-clockwise direction in the northern hemisphere and a clockwise direction in the southern hemisphere.

Answer 2

Pressure systems are caused by the differential heating of the land and sea and sometimes within the land and sea by the sun.So the sun is the root cause for the pressure systems to develope.