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Geog 111 Lecture Outline: Introduction to Earth's Hydrosphere
Update: 7/27/05

Last few lectures: brief overview of the atmosphere, climate and weather

1. Composition of the Atmosphere

2. Vertical Structure of the Atmosphere

3. Weather and Climate

Introduction to the Hydrosphere

1. The Nature of Water

McKnight fig 9.2

Can be a solid (ice), liquid (water) or gas (water vapor)

Processes which cause it to change from one state to another

Can absorb much energy (heat)

Water contracts (down to 39 degrees)

Water also readily dissolves other substances

...look in more detail at the movement of water: the hydrologic cycle

2. The Hydrologic Cycle

McKnight fig 9.4

Animation) Hydro Cycle

McKnight fig 9.5 Hydro Cycle

Residence Times: water remains for variable amounts of times at different stages in the hydro cycle

Given that: look at seven components of the hydrological cycle and corresponding physical processes

2a. Surface to Air Water Movement
2b. Air to Surface Water Movement
2c. Movement on and Beneath Earth's Surface
2d. The Oceans
2e. Permanent Ice
2f. Surface Waters
2g. Underground Water

2a. Surface to Air Water Movement

Two primary sources: surface waters and land

Surface Waters as source...

McKnight 6.3: Evaporation: How it Works

Land as source...

McKnight 9.5: hydro cycle

Transpiration: water entering the air from the land

2b. Air to Surface Water Movement

Processes of condensation and precipitation

Condensation is the opposite of evaporation

Precipitation originates in clouds (which consist of water vapor)

Overall balance between worldwide evaporation and worldwide precipitation

2c. Movement on and Beneath Earth's Surface

McKnight 9.5

Geographic imbalances...

Due to advection: horizontal movement of moisture in the atmosphere

Would suggest that the oceans over time should dry up, and land should be flooded

The water that falls (precipitates) on land has a complicated path

Runoff is approximately 7% of all moisture circulating in the global hydro cycle

Next: the places in the hydro cycle where water is stored a bit longer: residence times

2d. The Oceans

Oceans as a Human Concept

One 'Global Ocean' but humans have divided that up into smaller areas

Characteristics of Ocean Waters

Characteristics of the ocean have geographic variations

Variations in chemical composition, temperature, and density

Chemical Composition Variations

Dissolved minerals make up about 3.5% of ocean water's bulk

Salinity is a measure of concentration of salts in ocean water

Salinity varies from place to place

Middleton fig 9.6: Oceans

Temperature Variations

Closely related to latitude

Density Variations

Density of water varies

Movement of Ocean Waters

Ocean in constant movement


Daily patterns of sea level fluctuations


ANIMATION) Ocean Currents


2e. Permanent Ice

McKnight 9.8: global ice

Most permanent ice is on land

Ice nomenclature

McKnight 9.9: Arctic Ice

McKnight 9.10: Antarctic Ice

WWW) International Ice Patrol Site

Ice floe: large flat chunk of ice that breaks off larger ice mass and floats independently

Iceberg: chunk of floating ice broken off from larger ice mass

McKnight 9.11: Permafrost

Next: water stored on earth's surface...

2f. Surface Waters

Holds about .25% (1/4 of 1%) of world's moisture supply


Lake: a body of water surrounded by land

Two conditions necessary for lake formation

McKnight fig 9.12: freshwater vs saltwater lakes

Uneven geographic distribution of world lakes

Most lakes are temporary...less than a few thousand years old

Wetlands: Swamps and Marshes

Rivers and Streams

Provide the means by which the land surface drains and by which water, sediment, and dissolved chemicals are moved seaward

Location and occurrence of rivers and streams related to precipitation

McKnight fig 9.18

Major river drainage basins: all the land drained by a river and its tributaries (branches)

2g. Underground Water

McKnight fig 9.4

About 2.5 times the water contained in lakes and streams

Usually stored near the surface

Broader distribution than surface water: almost everywhere underground

Porosity: percentage of the total volume of the material that consists of voids (pore spaces or cracks) that can fill with water

The movement of water underground is also very important

Permeability: ability to transmit underground water; ability to allow water to move through the material: determined by size of pores and degree of interconnectedness

The amount of and rate at which water moves through subsurface material depends on porosity and permeability

Underground water is stored in aquifers

McKnight fig 9.A: Ogallala Aquifer

Aquifers: greek aqua = water and ferre = to bear

McKnight fig 9.19: Components of an Aquifer

aquicludes: underground water storage that is porous, but not permeable

Zone of aeration: mixture of solids, water, air

Zone of saturation: right below the zone of aeration

Zone of confined water: in some areas of the world, another aquifer below the zone of saturation and separated by a aquiclude

Waterless zone: at some depth, 5-6 miles, there is no longer any water

Sum: Introduction to the Hydrosphere

Most diverse of the earthly spheres

Encompasses oceans, lakes, rivers, wetlands, underground water, frozen water in the form of ice, snow, glaciers, water vapor in the atmosphere and moisture stored in plants and animals

1. The Nature of Water

2. The Hydrologic Cycle

E-mail: Geog 111 Main Page and Course Description krygier teaching page. krygier top page.

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