Railsback's Some Fundamentals of Mineralogy and Geochemistry Global climate zones Ia: building an idealized simple view Vertical Map view Climate Zones Wind Belts cross-section and Zones 30°N H H H H H H Subtropical Highs Horse Latitudes Hadley (anticyclones) Cell Easterlies Trade Tropics (Northeasterlies) Winds Greatest Rising warm air Intertropical solar L L L L L L L 0° Convergence Doldrums heating Zone (ITCZ) Easterlies Trade Tropics (Southeasterlies) Winds Hadley Cell H H H H H H 30°S Subtropical Highs Horse Latitudes (anticyclones) This diagram is the first of three building a typical Earth's surface is heated most near the equator, and the winds at Earth's surface turn according to the Coriolis Effect schematic representation of Earth's surface atmos- so air is heated most there. That warmed air rises, as sug- (right in the Northern Hemisphere; left in the Southern Hemisphere), pheric pressure, surface winds, and tropospheric gested above, and moves away from the equator high in the making the Earth-surface winds of both cells easterlies. circulation. This (Part Ia) and the next (Part Ib) are troposphere. That air sinks at about 30° N and S, and some pedagogical steps to the full representation in Part Ic. of it returns across Earth's surface to the equator to close Parts II to V then expand on that model. the Hadley Cells that are shown at left above. In map view, LBR 2/2013 GlobalClimateZonesIa02.odg Railsback's Some Fundamentals of Mineralogy and Geochemistry Global climate zones Ib: building an idealized simple view Vertical Least solar Map view Climate Zones Wind Belts cross-section and Zones heating Sinking cold air Polar Cell H Polar High Polar Easterlies L L L L 60°N Subpolar Lows Polar Front 30°N 0° 30°S L L L L Subpolar Lows 60°S Polar Front Polar Cell Polar Easterlies H Polar High Least Sinking cold air solar heating This diagram is the second of three that build a Earth's surface is heated least at the poles, and Polar Cells that are shown at left above. In map view, the winds at typical schematic representation of Earth's surface so air cools most there. That cold air sinks near the poles, Earth's surface turn according to the Coriolis Effect (right in the atmospheric pressure, surface winds, and tropospheric as suggested above, and moves away from the poles across Northern Hemisphere; left in the Southern Hemisphere), making the circulation. This (Part Ib) and the previous (Part Ia) are the Earth surface. That air finally warms enough to rise at Earth-surface winds of both cells easterlies. pedagogical steps to the full representation in Part Ic. about 60° N and S, and some of it returns high in the tropo- Parts II to V then expand on that model. sphere to sink again at the poles and thus to close the LBR 2/2013 GlobalClimateZonesIb02.odg Railsback's Some Fundamentals of Mineralogy and Geochemistry Global climate zones Ic: an idealized simple view Vertical Map view Climate Zones Wind Belts Weather cross-section and Zones Polar Cell H Polar High Dry Polar Easterlies 60°N Subpolar Lows Polar Front Rainy Ferrel L L L L Cell Temperate Westerlies Winter wet; summer dry 30°N H H H H H H Subtropical Highs Horse Latitudes Dry (anticyclones) Hadley Winter dry; summer wet Cell Easterlies Trade Tropics (Northeasterlies) Winds Intertropical L L L L L L L 0° Convergence Doldrums Rainy Zone (ITCZ) Easterlies Trade Tropics (Southeasterlies) Winds Hadley Cell Winter dry; summer wet H H H H H H 30°S Subtropical Highs Horse Latitudes Dry (anticyclones) Winter wet; summer dry Temperate Westerlies Ferrel Cell L L L L Subpolar Lows Rainy 60°S Polar Front Polar Easterlies Polar Cell H Polar High Dry The diagram above is a typical schematic repre- Atmospheric circulation is driven by rising of warm air at the the poles warms and rises at about 60° N and S, and the air that sentation of Earth's surface atmospheric pressure, equator (at the latitude of maximal solar heating) and by sinking returns aloft to the pole closes the Polar Cells. In between, the Ferrel surface winds, and tropospheric circulation. It of cold air at the poles (at the latitude of minimal heating). On Earth, Cells mirror the vertical flow at 30° and 60° N and S, with each cell mimics diagrams in many introductory climatology the air that has risen from the equator sinks at about 30° N and S, like a ball bearing rolled by the other two cells. Earth-surface move- and oceanography textbooks. Parts II to V of this and some of that air returns across Earth's surface to the equator to ment of air in these three kinds of cells gives the surface series expand on this theme in a little more detail. close the Hadley Cells. The air that has sunk and moved out from winds belts shown here. LBR 2/2013 GlobalClimateZonesIc02.odg Railsback's Some Fundamentals of Mineralogy and Geochemistry Global climate zones II: an idealized simple view, with weather Vertical Map view Climate Zones Wind Belts Weather cross-section and Zones Polar Cell H Polar High Dry Easterlies 60°N Subpolar Lows Polar Front Rainy Ferrel L L L L Cell Temperate Westerlies Winter wet; summer dry 30°N H H H H H H Subtropical Highs Horse Latitudes Dry (anticyclones) Hadley Winter dry; summer wet Cell Easterlies Trade Tropics (Northeasterlies) Winds Intertropical L L L L L L L 0° Convergence Doldrums Rainy Zone (ITCZ) Easterlies Trade Tropics (Southeasterlies) Winds Hadley Cell Winter dry; summer wet H H H H H H 30°S Subtropical Highs Horse Latitudes Dry (anticyclones) Winter wet; summer dry Temperate Westerlies Ferrel Cell L L L L Subpolar Lows Rainy 60°S Polar Front Easterlies Polar Cell H Polar High Dry Part I of this series showed a schematic pattern of atmos- Earth's easterlies are relatively constant because they are are more variable. The westerlies' changes in flow, as transient pheric circulation on Earth. This page changes that presentation driven by the constant heating (and low pressure) at the highs and lows move through the middle latitudes, give by suggesting some variability of the westerly winds. That vari- equator, and by the constant cold (and high pressure) at the variable weather that characterizes the middle latitudes. ability is shown here as variation through space, but it is also a the poles. The westerly winds, as the Earth-surface variability through time: it is the weather of the westerlies belt. expression of the more secondary or ancillary Ferrel Cells, LBR 2/2013 GlobalClimateZonesII02.odg Railsback's Some Fundamentals of Mineralogy and Geochemistry Global climate zones III: an idealized simple view, with seasons and weather Understanding the time and place of maturation of source rocks for petroleum requires an understanding of July January past geothermal gradients. Attempts to estimate past geothermal gradients commonly involve modeling of the Summer Winter flow of heat through layers of sedimentary rock, as shown below. L L L H L L L L H H H H H H H H H H H H L L L ITCZ L L L L L L ITCZ L L L H H H H H H H H H H H H L L L L L L L H Winter Summer Parts I and II of this series showed a schematic pattern of right one shows the southward shift in southern-hemisphere In the second, the polar region of the winter hemisphere atmospheric circulation on Earth. This page enlarges on that summer. One can think of this in two ways. In the first, the becomes colder and its cold area becomes larger, pattern by showing how the latitude of pressure zones and zone of maximum solar heating moves into the summer hemi- effectively pushing the cells and ITCZ toward the wind belts changes with the seasons. The left panel shows sphere, and so the equatorial low-pressure belt and Inter- summer hemisphere. the northward shift in northern-hemisphere summer, and the Tropical Convergence Zone (ITCZ) move into that hemisphere. LBR 2/2013 GlobalClimateZonesIII02.odg Railsback's Some Fundamentals of Mineralogy and Geochemistry Global climate zones IV: an idealized simple view, with seasons and continents Understanding the time and place of maturation of source rocks for petroleum requires an understanding of July January past geothermal gradients. Attempts to estimate past geothermal gradients commonly involve modeling of the Summer Winter flow of heat through layers of sedimentary rock, as shown below. L L L H L L L L H H H H H L L H H H H L L L L L L L L L L L L L L H H H H H H L H H H H H L L L L L L L H Winter Summer Part III of this series showed a schematic pattern of atmos- undergo seasonal temperature changes far more extreme to give pronounced areas of high pressure. Thus, to a climatolo- pheric circulation on Earth. That simplified Earth had a uniform than those of oceans. As a result, warmed air rises from gist, “continent” might be defined as “a land mass sufficiently surface, presumably of a global ocean of water. Earth of course continents in summer to give lows that disrupt the zone of large to develop seasonal anomalies of atmospheric pressure”. has continents of land, which are suggested here with tan high pressure in the Horse Latitudes, so that the sub- Part V of this series considers what happens when a very ovoids.