Global Average Barometric Pressure January Figure 4 11

Global Average Barometric Pressure: January Figure 4. 11

Global Average Barometric Pressure: July Figure 4. 11

Animation of Global Wind Circulation https: //www. youtube. com/watch? v=Ye 45 DG kq. Uk. E

Primary High Pressure & Low Pressure Areas • Equatorial low pressure zone: (aka Intertropical Convergence Zone) band of cloudiness & abundant precipitation. Thermally induced • Polar high pressure cells: subsiding air, stronger in winter. Associated with minimal precipitation. Thermally induced • Subtropical high pressure cells: areas of subsiding air, dry climates when near west side of continents. Dynamically induced • Subpolar low pressure cells: mean locations are Iceland & Aleutian Islands. Cause winter precip. (mid-latitude cyclones) Dynamically induced • The above pressure cells move north and south in response to seasonal changes in the subsolar point. Same w/ wind systems.

Primary Wind Systems • Trade Winds: most constant of all wind systems. Zone source region for tropical storms & hurricanes. • Westerlies: intensity positively related to Equator. Polar temperature differences. What season are they strongest? Which hemisphere the most persistent & strongest? • Polar Easterlies: stronger in winter • Polar Front: (not a wind) boundary where polar easterlies and the westerlies converge, bad weather zone

General Atmospheric Circulation: This is similar to your model to know! Figure 4. 13

Upper Atmospheric Circulation • Jet Stream: the core of upper-level westerly geostrophic winds (parallel to isobars), generally of high velocity. • Rossby Waves are found in the upper-air westerly circulation of the polar jet stream • http: //goo. gl/Q 2 k 47 H

Cross Section of General Atmospheric Circulation Figure 4. 13

Jet Streams Figure 4. 17

Local Winds • defined

Monsoonal Wind Systems • Seasonal wind changes that happen at a regional/continental scale due to seasonal reversals of onshore-offshore temperature differences. • Summer: onshore circulations, rain! • Winter: offshore circulations, dry • Where? S & SE Asia, Eq. Africa, a bit of S. America

South Asian Summer Monsoon