Grade 8 Science Unit 1 Water Systems on

Grade 8 Science Unit 1: Water Systems on Earth

Why do We Not Run Out of Water? ? Because of the: WATER CYCLE

The Water Cycle. . .

The constant cycling of water through the processes of : Evaporation&Condensation. conde nsatio Water is constantly changing from (gas liquid) and back again. This driven by the sun’s energy.

Sources of Fresh Water 1. 2. 3. 4. 5. Lakes, ponds and wetlands Streams and rivers Ground water Run Off Glaciers

Glaciers. . . A moving mass of snow and ice. Found in areas where it is so cold the snow remains all year.

Glaciers Almost 66% of all fresh water on Earth is in glaciers ◦ Glaciers form from layers of snow falling over many years ◦ Glaciers melt slowly under their own weight, and slowly flow downhill ◦ Glaciers cover about 10% of the Earth’s surface ◦ Alpine glaciers (aka valley) found in mountains ◦ Continental glaciers (aka ice sheets) cover huge areas of land. (c) Mc. Graw Hill Ryerson 2007

Glaciers in mountains and on the continent of Antarctica

Glaciers slow down the Water Cycle by storing big amounts of frozen fresh water. Some water thaws in the hot summer months. They give us information about the Earth’s past climates. ( samples) ◦ Glaciers flow until they reach an ocean, where crevasses open and icebergs fall off

Water trapped in glacial ice

Glaciers and Global Warming In the last 100 years the average surface temp. Has increased by 0. 5 o. C. The world’s glaciers are melting at a quicker paces than ever before.

Melting Greenlan d Glacier

Receding Athabasca Glacier in Alberta It has receded 1. 5 km since 1843.

What does this mean? Ocean waters may rise Flood rivers If they disappear, rivers may dry up.

Homework Answer questions 1 -5 on p 302 Watch the video-Chasing Ice