SCIENCE 1-12-16
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•No new water is created•Water is cleaned through the water cycle•Water is always moving•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• Condensation – process of water vapor becoming
liquid water when it cools• 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
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.
•Most of the freshwater is in glaciers and ice caps.
• 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.
• 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.
•Without these greenhouse gases, the earth would be extremely cold.
•Many human activities increase the amounts of greenhouse gases in the atmosphere.
• 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.
• This intensifies the water cycle.
INTENSE WATER CYCLE
• 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.
ACID RAIN
• 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.
EFFECTS OF ACID RAIN
• 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.
• Acid rain deteriorates buildings, statues, etc.