Seawater Ion Concentrations

Ion Atomic Weight Concentration Concentrationmg/L (ppm) mole/L

Cl- 35.5 1.90 x 104 5.3 x 10-1

Na+ 23 1.08 x 104 4.7 x 10-1

Mg++ 24.3 1.29 x 103 5.3 x 10-2

Ca++ 40 4.12 x 102 1.0 x 10-2

Fe+3 55.8 6 x 10-6 1 x 10-10 "best" current

estimate

*Fe+3 55.8 2 x 10-3 4 x 10-8

* Text tables - Seawater: Its composition, properties and behavior, Open University, 1989.

Inventory of H2O on Earth(S ~ 1.5 x 109 km3)

World water supply consists mainly of the salt water contained in the oceans (left). The world's fresh water comprises only about 3% of the total supply; three-quarters of it is locked up in the world's polar ice caps and glaciers and most of the rest is found as ground water or in lakes. The very small amount of water in the atmosphere at any one time (top right) is nonetheless of vital importance as a major energizer of weather systems. (Penman, Scientific American, 223, 98-108, 1970 (Sept).) Equivalent Depths (m) if spread over entire Earth (5.1 x 108 km2) Water vapor 0.03Surface water (lakes and rivers) 0.4 - 1.0Groundwater 15 - 45Ice and snow 50 - 120Oceans 2700

Mean Annual H2O Fluxes (cm/yr)

P E Q

Earth 100 100 Ocean 110 120 -10Land 70 45 25 * **

* River discharge (Q) from land equals Q to ocean, but total surface area used for ocean and land differ by a factor of ~2.5.

** Land average Q/P ~ 35%

Water Vapor in the Atmosphere (mm)

Polar (winter) 2Polar (summer) 8Mid latitude (winter) 10Mid latitude (summer) 20Equatorial 44

•factor of 20 in amounts of water vapor throughout entire atmosphere colummn at any given time: high in tropics, low at poles.•results primarily from very large difference in amount of water vapor that warm air can hold, compared to cold air.

t (H2O vapor) ~25 mm /????????

Hydrologic Budget: Reservoirs and Fluxes

Figure 2.1 - The hydrologic cycle. Numbers in parentheses represent inventories (in 106 km3 for each reservoir. Fluxes are in 106 km3 per year. (Data from Tables 2.1 and 2.2).

1. River Q (3.7x104 km3/yr) = Vapor (NET) from ocean

2. Q/P (fraction of runoff) = (3.7x104) / (11x104) = 34%

3. tH2O(ocean) = (mass of water in ocean) / Q(rivers) = (1.37x109 km3) / (3.7x104 km3/yr) = 4x104 yrs

4. tH2O(vapor) = (mass of water in atm) / [P(land) + P(ocean)] = (1.3x104 km3) / [(11 + 39) x 104 km3/yr] = (2.6x10-2 yr) x (3.65x102) day/yr = 9.5 days

Hadley Cell Circulation

ITCZ -• air from both hemispheres, flowing toward equator, must rise.• rain forms, releasing more energy to cause further vertical convection (positive feedback).

30° N and S• zones of subsiding air - hence low precip rates, and includes many of the major deserts of the world.