Atmospheric composition:

Atmospheric stratification: In terms of pressure and composition, the atmosphere grades upward without obvious breaks, however considered in terms of temperature, the atmosphere has four distinct zone, each characterized by a distinct thermal gradient:

Atmospheric circulation: Atmospheric circulation is primarily driven by two things: Solar energy and the Earth's rotation.

Climate vs weather:

Climate zones: Large regions with characteristic climates. If there were no continents, Earth's geographic climate zones would be simple. Actual climate zones represent interaction between atmosphere, ocean, and land masses of varying elevation, heat, and reflectivity.


World's primary reservoir of water, dissolved ions, and heat.

Composition: Ocean salinity is measured in parts per thousand (per mil). Varies between 33 per mil and 37 per mil. Solutes are generally ions. When you evaporate sea water, typical evaporites include:

Salinity: The concentration of ions in water at a given time and place.

Processes that increase salinity:

Processes that decrease salinity:

Ocean water density distribution:

Note: except for a few limited regions, there is no significant mixing of surface and deep waters. Those places are: In both regions, surface water chills and sinks, spreading out in the deep oceans.

Currents: In today's world, ocean circulation is mostly driven by temperature gradients. At the poles, water is chilled and sinks into the deep layer, then spreads along the ocean floor toward equator. There it rises, warms, and moves toward poles. Thus, at any region, there are cold deep currents and warm surface currents flowing in roughly opposite directions. This is an ice-house world that tends to confine heat to the tropics.
Greenhouse vs. Ice-house worlds: Fossil record shows that in the Cretaceous, the north slope of Alaska (which was at about the same latitude as now) had climate like that of New England. At this time, ocean circulation seems to have been driven by salinity. In it, equatorial waters evaporated, leaving warm but very saline surface layers. These would sink and spread toward the poles, carrying heat with them. Thus, heat was more evenly distributed and polar regions had warmer climates.

Some oddities:

The Gulf Stream.

  • During Nothern Hemisphere summer:

    Key concepts and vocabulary: