1) Global and Regional Atmospheric Circulation

Temperature and Humidity Relation

• Non-linear relationship; exponential growth as temperature increases.

• Warmer air can hold more moisture; leading to lower relative humidity if water content remains unchanged.

Hadley Cells and Atmospheric Circulation

• Fundamental circulation patterns near the equator: hot, humid air rises, moves towards poles, cools, sinks, and returns towards the equator.

• Intertropical Convergence Zone (ITCZ) is where Hadley cells converge, characterized by rising humid air.

Factors Affecting Air Density

• Hot air rises due to lower density; humid air also lowers density.

• Water vapor (H₂O) displaces heavier molecules, reducing overall air density.

Atmospheric Behavior by Latitude

• Regions around 30° North/South experience dry, sinking air leading to deserts (e.g., Sahara, Mojave).

• Polar regions experience cold, dense air sinking with low precipitation; characterized by cold winds and severe weather.

Coriolis Effect

• Causes deflection of winds: to the right in the Northern Hemisphere, to the left in the Southern Hemisphere.

• Air rotates clockwise around high pressure and counterclockwise around low pressure systems.

Trade Winds and Weather Patterns

• Trade winds blow consistently from east to west; named for the direction they originate.

• Westerlies and easterlies (polar) elsewhere; differences primarily due to temperature gradients.

Jet Streams

• Polar and subtropical jet streams influencing weather patterns; generally move west to east.

• Stronger in winter due to temperature contrasts; help determine flight paths for aircraft.

Monsoons

• Seasonal reversal in airflow between land and ocean due to differing heat capacities.

• In summer, land heats more rapidly than ocean, causing rising humid air and resulting rains; the opposite in winter.