A westerly wind blows eastward, because winds are named for their source
Meteorologists label wind by where it comes from, not where it goes, so a northerly pushes south and a westerly heads east. It trips people up constantly. Behind the naming sits simple physics: air rushing from high pressure to low, bent by Earth's spin everywhere except exactly on the equator.
Wind is air, or any gas, moving across a planet's surface, and its study is called anemology. Pressure differences, mostly created by uneven heating, set air in motion. On a global scale, two factors dominate: the equator absorbs far more solar energy than the poles, and the planet rotates, deflecting moving air through the Coriolis effect. Near the ground, friction slows the wind and steers it further into low-pressure zones; higher up, away from that drag, it settles towards a balance between pressure and rotation, flowing parallel to the isobars.
Winds span every scale. Thunderstorm outflows last minutes, sea and land breezes swap direction daily along coasts, mountain and valley breezes follow the terrain, and heating over high plateaus drives monsoons. Brief spikes are gusts, blasts lasting around a minute are squalls, and sustained winds climb through breeze and gale to storm and hurricane. Internationally, sustained speed is measured ten metres up and averaged over ten minutes, while the United States uses a one-minute average for tropical cyclones.
Measuring it takes some ingenuity. Weather vanes and airport windsocks show direction, and a windsock's droop hints at speed. Anemometers usually spin cups or propellers, but research instruments time ultrasound pulses or track how moving air cools a heated wire, and pitot tubes read the pressure difference between two tubes.
Wind has shaped both landscapes and history. It builds fertile loess soils, erodes rock, carries desert dust across great distances, fans wildfires and scatters seeds, insects and birds. People harnessed it for sailing ships, mills, electricity and balloon flights, while shear near storms endangers aircraft. Beyond Earth, the Sun streams out a solar wind, planets leak light gases to space, and the fiercest planetary winds in the Solar System blow on Neptune and Saturn.
Source: Wind
