The cool breezes that gently spin our “Spinning Leaves” is a mystery to most of us. The way our kinetic sculptures capture the wind is almost magical. Of course most of us have also seen the extraordinary power of the wind from a Hurricane, or the devastation caused by a Tornado. What causes the wind to blow?
First and foremost is the difference in air temperature. We all know heat rises. When the sun heats the earth it warms the air above it causing it to rise. Cool air replaces the rising hot air and we have wind. You can observe this in the ripples that form on a lake as the rising sunwarms the early morning air.
Looking at the wind on a global scale we see this hot air rising from the equator and moving north. As it cools it falls back to the earth’s surface. This atmospheric circulation pattern known as a Hadley Cell - low pressure and converging winds, plus something known as the Coriolis effect - produces what are known as tropical easterlies or “trade winds.”
The Coriolis effect - stay with me - is the deflection of winds moving along the surface of the Earth to the right of the direction of the earth’s rotation in the Northern hemisphere, and to the left of the Earth’s rotation in the Southern Hemisphere. This can be seen in those satellite pictures of a large cyclones where winds around the center will appear to move counter clockwise in the North, and clockwise in the south.
This combination of temperature and barometric pressure - air bumping into air and the earths surface - generates winds of different speeds. High barometric pressure produces calm weather, whereas low barometric pressure results in unsettled weather and higher wind speeds. So next time you’re enjoying the simple play of your Hypnartic Artworks wind sculpture, think of the complexity blowing in that wind.