Winds are the horizontal movement of air molecules.
- The direction of the wind is given as the direction from which the wind is coming
- Wind direction is measured by a wind vane.
- Wind speed is measured by an anemometer. Wind speeds can also be measured using Doppler radar.
Air motion is produced by horizontal pressure gradients.
- Horizontal pressure gradients represent differences in pressure between one location and another, after accounting
for differences associated with changes in elevation.
- The direction of pressure gradients is from high to low pressures, perpendicular to the isobars.
- The strength increases with decreasing distance between the isobars.
Pressure gradients at the surface and aloft form when air is unevenly heated, creating thermal circulations.
- Sea and land breezes are examples of thermal circulations formed from unequal heating and cooling of land and
- Mountain and valley winds, SantaAna, and foehn winds are other examples of local winds.
The Earth's rotation creates the Coriolis effect.
- The Coriolis effect acts as an additional force that deflects wind motion to the right in the northern hemisphere
and to the left in the southern hemisphere.
The strength of the Coriolis force increases with increasing wind speed as well as with latitude.
- It is always directed perpendicular to the object's motion.
When only the pressure gradient force and Coriolis force affect the winds, they are called geostrophic winds.
- Geostrophic winds blow p