WATER

Water

Important properties of water.

Water is a unique substance - mostly due to nature hydrogen bond

Occurs in 3 states of matter at earth's surface.

Unlike many substances the solid is less dense than liquid - so ice floats. This keeps water bodies from freezing permanently

- can easily be redistributed around world due condensation, evaporation

melting and boiling points are much higher than for chemically similar substances
high heat capacity - amount of heat required raise T unit volume by one degree
high heat of vaporization - one of highest of all liquids.
As a result, water is a major mechanism of heat transfer on earth
high surface tension - a measure how strongly molecules of a liquid attracted to each other.
absorbs radiation. Strongly absorbent in infrared and ultraviolet.
Solvent - excellent due to fact molecules are polar; attraction of the ends of polar water molecules for oppositely charged ions greater than attraction of ions for one another.

Hydrologic cycle - is driven by sun

Hydrosphere covers 71% of earth: 1.41 x 109 km³. If evenly spread it would be 3 km deep everywhere

4 reservoirs:

oceans 97.3%
continents 2.7%
atmosphere .001%
earth's interior

2.59% fresh
1.984 in glaciers (77%)
.592 underground (groundwater)
.007 lakes
.005 soil moisture
.001 atmosphere - 13,000 km³
.0001 biota - 2000 km³
.0001 rivers ~ 50% south America, 25% Asia. (in one year 41,000 km³ in rivers)

Rains

500,000 km³/yr, 1/5 on land 4/5 on ocean
of that on land, 65% evaporates or transpires (through plants)
rest runs off or soaks in

World av. 100 cm/yr. - US av. 76 cm/yr. rain - SE PA 110 cm/yr.
SE PA runoff 39%, evaporation, transpiration 57%, rest infiltrates

if evaporation>rain have water deficiency

- eastern 31 states surplus
- western 17 have deficiency