15 - 1 The Water Cycle

Where did all the water come from? Early Greeks thought it was supplied by rain and snow Earth’s surface receives 5 times as much water as rivers can carry off Where does it come from? Where does it all go?

Movement of Water Two/thirds or 70 % of earth is covered in water Lakes Streams Oceans Ice Groundwater

Water Water is found in living tissues

Water Vapor and Clouds Small invisible particles Clouds and Fog

The Water Cycle Constant movement of water between land, air, and water

Evaporation Liquid changes to a gas Every year: 500,000 km3 into oceans 86% from the ocean

Transpiration Process in which plants and animals release water vapor into the atmosphere

Evapotranspiration Total water loss from an area: Evaporation

Condensation Water changes from a gas to a liquid When water vapor become cooler it condenses

Precipitation Any water that falls to the Earth Rain Sleet Snow Hail 75% falls in the oceans

Water Budget Think of your own budget? Precipitation – income Evapotranspiration and runoff - expenses

Determining Factors Temperature Vegetation Wind Precipitation duration

Drought Evapotranspiration > precipitation

Flood Evapotranspiration < precipitation

Water Use Each person, every year: 20,890.5 gallons 90% of water used by cities and industry is returned as wastewater

Conservation of Water Conserve water Desalination – removing salt from ocean water Expensive