7.6: Accessible Descriptions
- Page ID
- 52332
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Figure 7.1.3: Energy Balances with Latitude
Graph showing the latitudinal distribution of Earth’s net radiation imbalance and resulting heat transport. The horizontal axis represents latitude from 90° south to 90° north, and the vertical axis represents net energy (in gigawatts per meter). The curve is positive in low latitudes near the equator, indicating a surplus of energy, and negative in higher latitudes toward both poles, indicating a deficit. The surplus region peaks at the equator and transitions to deficit around mid-latitudes. Arrows indicate that heat is transported from the equatorial surplus regions toward higher latitudes in both hemispheres. Approximate net radiation values for various latitudes are provided in Table 7.6.1.
| Latitude (°) | Net radiation (GW/m) | Region classification |
|---|---|---|
| 90 S | -1.3 | Deficit |
| 60 S | -1.5 | Deficit (minimum) |
| 45 S | -0.8 | Deficit |
| 30 S | 0.0 | Transition |
| 15 S | 1.5 | Surplus |
| 0 | 2.5 | Maximum surplus |
| 15 N | 1.5 | Surplus |
| 30 N | 0.0 | Transition |
| 45 N | -0.8 | Deficit |
| 60 N | -1.5 | Deficit (minimum) |
| 90 N | -1.3 | Deficit |
Figure 7.3.2: Average Position of Pressure Systems in January
Global map showing average sea-level pressure patterns for January, with contour lines labeled in hectopascals (hPa). In the Northern Hemisphere, a low-pressure center over the North Pacific (Aleutian Low) is shown with values around 1000 hPa near 50–60°N, and another low over the North Atlantic (Icelandic Low) also near 1000 hPa around 60–70°N. A strong high-pressure system over Asia (Siberian High) reaches about 1030 hPa between roughly 40–60°N. Subtropical high-pressure systems appear in the Southern Hemisphere, including the South Pacific, South Atlantic, and southern Indian Ocean highs, each around 1020 hPa near 30–40°S.
Near the equator (0–10° latitude), a band of lower pressure called the equatorial trough is indicated, with values around 1008–1010 hPa. In the Southern Hemisphere mid- to high latitudes (about 50–70°S), a continuous belt of low pressure known as the circumpolar trough is shown, with values generally between about 990 and 1000 hPa. Additional continental low-pressure regions in tropical land areas are marked with pressures around 1005–1010 hPa.
Overall, the map shows higher pressures in the subtropics (~1015–1025 hPa), lower pressures near the equator (~1008–1012 hPa), and pronounced low-pressure systems in subpolar regions (~990–1000 hPa), with strong seasonal contrasts in the Northern Hemisphere during winter.
Figure 7.3.3: Average Position of Pressure Systems in July
Global map showing average sea-level pressure patterns for July, with contour lines labeled in hectopascals (hPa). In the Northern Hemisphere, high-pressure systems dominate over the oceans, including the Hawaiian High in the North Pacific (around 1020–1025 hPa near 30–40°N) and the Bermuda or Azores High in the North Atlantic (also about 1020–1025 hPa near 30–40°N). Over Asia, a strong low-pressure system known as the Tibetan Low is centered around 1000 hPa near 20–30°N.
Near the equator (0–10° latitude), the equatorial trough is present with pressures around 1008–1010 hPa. In the Southern Hemisphere, subtropical high-pressure systems are located over the South Pacific, South Atlantic, and southern Indian Ocean, each around 1020–1025 hPa near 30–40°S. Farther south, a continuous belt of low pressure called the circumpolar trough occurs between about 50–70°S, with pressures around 990–1000 hPa. Over Antarctica, a strong high-pressure system (Antarctic High) reaches about 1030–1040 hPa near 80–90°S.
Overall, the map shows stronger oceanic high-pressure systems in the Northern Hemisphere during summer, a continental low over Asia, and persistent Southern Hemisphere pressure belts.
Figure 7.4.1: Three Circulation Cells and Jet Streams
Diagram showing large-scale atmospheric circulation in the Northern Hemisphere from the equator to the North Pole. The horizontal axis represents latitude, labeled at the equator (0°), about 30°N, about 60°N, and the North Pole (90°N). Three circulation cells are depicted. From the equator to about 30°N, the Hadley cell shows rising air at the equator, poleward flow aloft, sinking air near 30°N, and return flow toward the equator at the surface. Between about 30°N and 60°N, the Ferrel cell shows surface flow toward higher latitudes, rising motion near 60°N, and return flow aloft toward 30°N. From about 60°N to the pole, the Polar cell shows rising air near 60°N, poleward flow aloft, sinking air over the pole, and surface flow back toward 60°N.
Two jet streams are indicated: the subtropical jet near 30°N and the polar jet near 60°N, both located near the tropopause. The tropopause is shown as a boundary that slopes downward from the equator toward higher latitudes. The diagram emphasizes that air rises at approximately 0° and 60°N and sinks near 30°N and 90°N, with jet streams forming at the boundaries between circulation cells.