GEO 130 - Hydrosphere

Earth's water coverage

71% of the surface is covered by water, making Earth a "water planet"

Water hemisphere

The Southern Hemisphere, where most of the ocean is

Land hemisphere

The Northern Hemisphere, where most land masses are concentrated

Four extraordinary characteristics of water

Frequent phase change, universal solvent, powerful heat transporter, unique density variation

Three states of water

Solid (ice), liquid (water), and gas (water vapor)

Importance of water's phase changes

Crucial for the biosphere; drives heat transfer and the water cycle

Latent heat of evaporation/condensation

Energy absorbed and released as water changes phase; powers weather systems

Hydrosphere

All the water on Earth, including its frozen part

Cryosphere

The frozen part of the hydrosphere

Where most of Earth's water is stored

The ocean (salty)

Where most of Earth's fresh water is stored

Glaciers (solid ice)

Land and atmospheric water

Small in quantity, but the most important water for life

Freshwater quantity problems

Drought and water mining

Freshwater quality problem

Pollution

Water mining

Pumping groundwater out faster than it refills

Water scarcity

Shortage of fresh water that remains regionally severe worldwide because supplies are unevenly distributed

Water-management projects

Engineering projects that move water to where it's needed to fix uneven distribution

California State Water Project

Water-management project in the United States

South-North Water Diversion Project

Water-management project in China

Desalination

Removing salt from seawater to make fresh water

Ashkelon Desalination Plant

Desalination plant in Israel

Hydrologic cycle (water cycle)

Movement of water between ocean and land through the atmosphere that keeps land supplied with fresh water

How the ocean loses water to the air

Evaporation

How land loses water to the air

Evapotranspiration

Evapotranspiration

Evaporation plus transpiration

Transpiration

Water vapor released into the air by plants

How both ocean and land gain water from the air

Precipitation

Land's water balance

Net gain: land receives more precipitation than it loses to evapotranspiration

Ocean's water balance

Net loss: the ocean evaporates more water than it receives as precipitation

Runoff

The land's surplus water flowing back to the ocean

Runoff split

About 95% surface runoff and about 5% groundwater

"Earth's desalination plant"

Nickname for the water cycle: evaporation leaves salt behind, so precipitation falls as fresh water for land ecosystems