|OBJECTIVE||Discover the different water ratios in the earth's total water supply.|
|OVERVIEW||The students will estimate how much water they think can be found in various locations on the earth in all its states; solid, liquid, and gas.|
|TOTAL TIME||20 minutes|
|SUPPLIES||Eight (8) 1000 ml beakers
|TEACHER PREPARATION||This can be done as a class demonstration or you can divide the students into pairs should you have enough glass jars. You can also shorten this experiment by using crushed ice instead of cubed ice. The crushed ice will chill the water quicker, causing condensation sooner.|
|SAFETY FOCUS||Flash Flood Safety|
Water is the most abundant and important substance on Earth. It is essential to life and is a major component of all living things. There are approximately 336,000,000,000,000,000,000 gallons of water on the earth, existing in three states; solid, liquid and gas. The sources for this water storage are the oceans, icecaps & glaciers, ground water, fresh-water lakes, inland seas, soil moisture, atmosphere, and rivers.
- Label beaker 1 "oceans" and fill it with 1000 ml of water.
- Label the following beakers: beaker 2 "glaciers & icecaps", beaker 3 "groundwater", beaker 4 "fresh-water lakes", beaker 5 "inland seas", beaker 6 "soil moisture", beaker 7 "atmosphere", and beaker 8 "rivers".
- Inform the students that the earth's total water supply has been reduced to 1000 ml as indicated in beaker 1.
- Ask the students how much water must be transferred from beaker 1 and placed in each of the remaining beakers.
- After all beakers have some water in them, write their estimates on the chalk board.
- Pour all water back into beaker 1, dry beakers 2 through 8, and add any water necessary to return beaker 1 to 1000 ml.
- Transfer the following amounts of water from beaker 1 to each of the remaining beakers.
- Glaciers & icecaps - 21.4 ml
- Groundwater - 6.1 ml
- Fresh-water lakes - 0.09 ml
- Inland seas - 0.08 ml
- Soil moisture - 0.05 ml
- Atmosphere - 0.01 ml
- Rivers - 0.001 ml
The students will be surprised how little water is found in each of the remaining beakers. The vast majority of water is found in the oceans; approximately 97.2%. The following are the percentages for each water source:
|Water Source||Water volume
|Glaciers & icecaps||7,000,000||2.14%|
|Total water volume||326,000,000||100%|
Despite the over abundance of rain we often receive, the atmosphere contains very little of the earth's total water supply.
A cubic mile of water equals more than one trillion gallons. If all the water in the atmosphere fell as precipitation at once, the Earth would be covered with only about 1 inch (2.5 cm) of water.
The 48 contiguous United States receives a total volume of about 4 cubic miles (6.4 cubic km) of precipitation each day. If all of the world's water was poured on the United States, it would cover the land to a depth of 90 miles (145 km). Each day, 280 cubic miles (450 cubic km) of water evaporate or transpire into the atmosphere.
Flash floods are the deadliest natural disaster in the world. They are caused by stationary or slow-moving thunderstorms that produce heavy rain over a small area. Hilly and mountainous areas are especially vulnerable to flash floods, where steep terrain and narrow canyons can funnel heavy rain into small creeks and dry ravines, turning them into raging walls of water. Even on the prairie, normally-dry draws and low spots can fill with rushing water during very heavy rain.
Take time to develop a flood safety plan-for home, work, or school, and wherever you spend time during the summer. The National Weather Service has additional information about flood safety and a brochure "Floods and Flash Floods...The Awesome Power".
When traveling or outdoors:
- Keep track of the counties, towns, rivers, and creeks along and near your route, so you will know if you are near a flood prone area.
- Take a weather radio with you wherever you go.
- Check the weather forecast before a trip or outdoor activity. Postpone your plans if flooding is forecast.
- Choose campsites AWAY from creeks and other low-lying areas.
- Be especially cautious at night, when dangerous rising water is more difficult to detect.
- Find out how to get local warning information, such as outdoor warning sirens or cable TV, or the NOAA Weather Radio.