SCIENCE

L1 WHERE IS EARTH’S WATER? Earth – The water planet People use water to travel ¾ of surface is covered by water It provides a home & food 3 states of water Solid (frozen) Liquid (melted) Gas (invisible water vapor)

ATLANTIC & PACIFIC OCEANS

ARCTIC & INDIAN

SOUTHERN OCEAN < 1% Oceans Seas 97% Lakes Rivers

“WATER, WATER, EVERYWHERE, NOR ANY DROP TO DRINK” SALT WATER FRESH WATER

SALT V. FRESH Most of the fresh water is frozen in the polar ice caps and glaciers You cannot drink salt water It has dissolved solids in it Salt from rocks & soil Rivers carry salt to the ocean We use ocean salt on food WATER TABLE

SALTINESS MORE Warm places where water evaporates quickly allows more salt to be quickly left behind (salt does not evaporate) Red Sea is very salty because there are deserts on three sides Most of Earth’s water is salty ocean water LESS Ocean water is less salty near the North and South Poles where the water evaporates less quickly Fresh water is found in glaciers and ice caps but it is not safe to drink Safe fresh water is found underground or in lakes, rivers, and streams

L2 WATER CYCLE Water is recycled Water is recycled No new water is created No new water is created Water is cleaned through the water cycle Water is cleaned through the water cycle Water is always moving Water is always moving The movement is called the water cycle The movement is called the water cycle

WATER CYCLE

THE WATER CYCLE Evaporation – process of changing liquid water to water vapor when it is heated Evaporation – process of changing liquid water to water vapor when it is heated Condensation – process of water vapor becoming liquid water when it cools Condensation – process of water vapor becoming liquid water when it cools Precipitation - any form of water that falls to Earth Precipitation - any form of water that falls to Earth Storage (collection) – water from precipitation sinks into soil, or it falls, flows, or seeps into the ocean Storage (collection) – water from precipitation sinks into soil, or it falls, flows, or seeps into the ocean

SUN’S ENERGY = POWERS THE WATER CYCLE

HUMAN IMPACT ON WATER CYCLE

FRESH WATER ON EARTH IS LIMITED Although 75% of the earth is covered in water, only 3% of the water is freshwater. Although 75% of the earth is covered in water, only 3% of the water is freshwater. Most of the freshwater is in glaciers and ice caps. Most of the freshwater is in glaciers and ice caps. Less than 1% of the freshwater on the earth is readily available. Less than 1% of the freshwater on the earth is readily available.

USABLE WATER IS VALUABLE Think about how many ways you use clean freshwater every day. Think about how many ways you use clean freshwater every day. Did you wash your face? Brush your teeth? Take a drink? Cook food? Use the toilet? Eat fresh produce? Wash your clothes? Did you wash your face? Brush your teeth? Take a drink? Cook food? Use the toilet? Eat fresh produce? Wash your clothes?

GREENHOUSE GASES Certain gases in the atmosphere help keep the earth warm. Certain gases in the atmosphere help keep the earth warm. Without these greenhouse gases, the earth would be extremely cold. Without these greenhouse gases, the earth would be extremely cold. Many human activities increase the amounts of greenhouse gases in the atmosphere. Many human activities increase the amounts of greenhouse gases in the atmosphere. This is believed to be causing global warming. This is believed to be causing global warming.

GLOBAL WARMING AFFECTS THE WATER CYCLE Warmer air causes more evaporation and warm air holds more water. Warmer air causes more evaporation and warm air holds more water. This intensifies the water cycle. This intensifies the water cycle.

INTENSE WATER CYCLE In areas around water, there may be more clouds and precipitation. In areas around water, there may be more clouds and precipitation. In areas that are away from bodies of water, there may be few clouds and less precipitation leading to dry soil, plants dying, wells drying up, etc. In areas that are away from bodies of water, there may be few clouds and less precipitation leading to dry soil, plants dying, wells drying up, etc.

ACID RAIN Combustion of fossil fuels adds sulfur and nitrogen compounds to the air. Combustion of fossil fuels adds sulfur and nitrogen compounds to the air. These compounds mix with the water vapor in the atmosphere and make it more acidic. These compounds mix with the water vapor in the atmosphere and make it more acidic.

EFFECTS OF ACID RAIN Acid precipitation causes water on the earth’s surface to be more acidic. Acid precipitation causes water on the earth’s surface to be more acidic. Many plants and animals cannot live in the more acidic conditions. They die and it affects everything in the food web. Many plants and animals cannot live in the more acidic conditions. They die and it affects everything in the food web. Acid rain deteriorates buildings, statues, etc. Acid rain deteriorates buildings, statues, etc.