Hydrologic Cycle

Water is Ubiquitous!

Biosphere- Water CycleHydrosphere

• Liquid waters of earth.

1. Oceans2. Lakes3. Streams4. 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 BudgetHow the water is divided

among:• Ocean• Land• Atmosphere

Proportions of waterremains relatively

stable on Earth. Only the distribution

differs (tropical vs desert).

Water CycleThe 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 MoveFrom

Atmosphere to Surface

1. Condensation2. Precipitation

From Surface to Atmosphere

1. Evaporation2. Transpiration3. Sublimation

Sublimation: from solid to gas without melting.

Snow or ice vapor

EvaporationFrom 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 N2 and O2. 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.

CloudsA 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.

PrecipitationWater droplets coalesce to form

precipitation.Gravity pulls it to the earths surface.• Hail• Rain• Sleet• Snow

PrecipitationInterception: 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 WaterTogether ground water and soil water

make up .5% of freshwater.

Ground Water Zones1. Unsaturated- soil and water 2. Saturated- ground water

Vadose: soil moisture

Water table: divides the 2 zones.

Zone of SaturationAquifer- 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 flowSeepage: ground

water flows to a stream channel, lakes, and wetlands

Hydraulic conductivity- the measure of the ability of a material to transport water.

Human ConnectionUnited States Family

Water IssuesThe amount of

water on earth remains constant.

World population- 7.111 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?