4.5 & 4.6 Global Wind Patterns & Watersheds

Global Wind Patterns

• The Earth’s atmosphere is held by gravity

• As the Earth rotates, the air circulates

• The heating and cooling changes the density of the air as it moves, due to convection (Hadley Cells)

Coriolis Effect

• Along with heat, rotation of the Earth deflects the wind as well

• Hot air in equator turns to the poles with a curve, since the Earth spins

Predictability of Wind Patterns

• The exchange of heat and Coriolis effect leads to patterns that are generally regular

• Ecosystems around the globe result from these exchanges of heat and rotation

Watersheds

• Watersheds are defined by the highest points/divides around them

• Tributaries - smaller rivers that leads to larger river that goes to the watershed

• Delta - Where the river meets the larger body of water

• Groundwater/aquifer

General Watershed

• Source zone - Head of the river (snow)

• Transition zone - between head, fully oxygenated, cooler

• Floodplain zone - river spreads out and more sedimentation, less oxygenated, warmer

• Flow because of gravity

General Watershed

• Rainwater that lands within the Watershed does one of two things:

  • Runs downhill across the land associated with the watershed until it joins the river or one of its tributaries

  • Percolates through the soil to join the groundwater

• Rainwater that lands at the divide between watersheds will run into either one watershed or the other

Human’s impact on Watersheds

• Logging - cut down trees and remove the roots that hold the soil in place

• Residential areas - pesticide and fertilizers use, pinhole leaks in cars, washed into river

• Industrial sites - waste and pollution into river

• Cities - Asphalt and concrete

• Livestock and cropland - animal waste, with fertilizer and pesticide use

• Dams - block the flow of crucial sediments that carry nutrients