Hydrologic Cycle
Water is Ubiquitous!
Biosphere- Water Cycle Hydrosphere Liquid waters of earth. 1. Oceans 2. Lakes 3. Streams 4. Glaciers Atmosphere Layer of gases surrounding earth. 1. Clouds 2. Vapor
Earth is a closed system: The water available on Earth, today, is the same water that has always been available and the only water that ever will be available!
How much Water do We Have?
Fresh Water ≤1 % of Earth’s water is available for the following: Support organisms such as: plants, bacteria, humans Support industry, agriculture Provide a source of recreation Hydropower plants- energy Transportation Habitats Waste processing
Earth’s Water Budget How the water is divided among: Ocean Land Atmosphere Proportions of water remains relatively stable on Earth. Only the distribution differs (tropical vs desert).
Water Cycle The actual path any given water molecule follows in a complete water cycle can be varied and complex and may not follow the exact path shown by a diagram.
Water is Always on the Move From Atmosphere to Surface 1. Condensation 2. Precipitation From Surface to Atmosphere 1.Evaporation 2. Transpiration 3. Sublimation Sublimation: from solid to gas without melting. Snow or ice vapor
Evaporation From liquid to vapor 80% of all water entering the atmosphere originates from the ocean. Transfers energy from the earth’s surface to the air above. Latent energy: hidden heat energy Latere- (Lat.) to lie hidden
Water Vapor Odorless, colorless gas that mixes with other gases in the atmosphere like N 2 and O 2. These gases make up 99% of the atmosphere. The amount of water vapor varies from less than 1% to 4% in the atmosphere.
Condensation Water vapor cools in the upper atmosphere to form drops or ice. Releases latent heat warming the air. The released heat may trigger storms.
Clouds A mass of liquid droplets or frozen crystals. 1. Earth’s water transportation system. in conjunction with wind 2. Determine how much of earth energy is absorbed. block solar rays 3. Alters temperature of air on earth’s surface traps heat on the surface
The process of evaporation and condensation purifies water naturally. Evaporation: only the water molecules leave the surface; the dissolved salts and other solids remain behind in solution. Condensation: when the water vapor condenses again it is pure. It may become contaminated as it falls through the atmosphere: sulfates and nitric oxides ( NOx) cause acid precipitation.
Precipitation Water droplets coalesce to form precipitation. Gravity pulls it to the earths surface. Hail Rain Sleet Snow
Precipitation Interception: falls on leaves or stems of plants. Percolation: moves down into the soil and ground water. Runoff: does not infiltrate soil but travels across the surface of land.
Ground Water Together ground water and soil water make up.5% of freshwater.
Ground Water Zones 1.Unsaturated- soil and water 2.Saturated- ground water Vadose: soil moisture Water table: divides the 2 zones.
Zone of Saturation Aquifer- body of earth material that has the ability to hold and transport water. Unconfined- “open” connected to the surface above. Confined- “closed” sandwiched between dense impermeable layer of earth.
Groundwater Movement Replenished by percolation from zone of aeration downward to zone of saturation. Recharge zone- where confined aquifer is exposed at the surface.
Groundwater flow Seepage: ground water flows to a stream channel, lakes, and wetlands Hydraulic conductivity- the measure of the ability of a material to transport water.
Human Connection United StatesFamily
Water Issues The amount of water on earth remains constant. World population billion & growing 783 million people do not have access to clean water. 2.5 billion do not have access to adequate sanitation. Demand for food, space, energy and clean water continues to rise. What can you do?