Water The only substance on Earth that exists in all 3 states of matter Solid- liquid- gas The Energy for the Water Cycle originally came from the Sun

Liquid Water The oceans hold 97% of the Earth’s liquid water

Fresh Water Only 3% of Earth’s water is Fresh Water

Groundwater most of Earth’s liquid Freshwater is underground

Ice, and Glaciers most of Earth’s fresh water is in ice water freezes at 0o Celsius

Glacial Ice: some important points About 10% of Earth land surface is currently covered by ice. Ice “advances” downhill, and away from the glacial centers. Short term: Ice melts at the edges at about the same rate as it advances so the total ice volume remains about the same. Long term: Climate change has a great affect on global ice volume, with some significant consequences. ~ 20,000 years ago, ice covered 3x more land than today. ~ Global ice volume is still shrinking. Why, and what are the consequences?

Water Vapor When water evaporates it becomes water vapor. There is approximately 12,900 km3 or 3,100 mi3 of water vapor in the Earth’s atmosphere.

Total amount of Water The total amount of water on Earth remains fairly constant. We drink the same water as the Dinosaurs drank We gain ~ 1 cup of water per year, from comets

pH of Water The pH scale ranges from 0 to 14. 0 is an Acid and 14 is a Base The pH of Water is 7, which means neutral

Precipitaion Precipitation falls on the Earth as rain, snow, sleet, or hail. Precipitation can run off the land, or accumulate in puddles, ponds, or Lakes. Accumulated water can soak into the ground, called infiltration. In higher elevations it can runs off mountains, or accumulates as snow.

Run Off In mountains when snow melts, or water runs down hill it forms streams, or rivers. The mountain is a divide and water flowing down one side of the mountain goes into a watershed.

Watershed and Divide A watershed is the area of land where all of the water that falls in it, and drains off of it, goes to a common outlet. Las Vegas gets its water from the Colorado Watershed. A Divide is the elevated boundary separating areas that are drained by different river systems. Water flowing on one side of a divide empties into one body of water, while water flowing on the other side empties into another.

Rivers and Streams In mountains when snow melts, or water runs down hill it forms streams, or rivers. Larger rivers are made up of smaller rivers and streams, called tributaries. These make up a River System.