midlatitude and highlatitude climates Flashcards
midlatitude climates extend from
subtropical zone to approximately 55° N and S latitudes.
The midlatitude climates range from those wit
strong wet and dry seasons to those with precipitation that is more or less uniformly distributed through the year. Temperature cycles also are quite varied (windward west coasts experience low annual ranges but annual ranges are large in the continental interiors
dry subtropical climate
s a poleward extension of the dry tropical climate, but because of the midlatitudelocation, the annual temperature range is greater. There is a distinct cool season at the time of low sun, which is accentuated by invasions of cold continental polar (cP) air masses that also bring frontal storms to the region. As is the case for the dry tropical climate, the dry subtropical climate type has both arid and semi-arid subtype
Mediterranean climateis located
along the west coasts of continents in the latitude range 30° to 45° N and S (distinguished by its annual precipitation cycle - wet winter and very dry summer). This is caused by the poleward movement of the subtropical high-pressure cells during the summer season, which brings dry cT air into the region
n terms of total annual precipitation, the Mediterranean climate typ
varies from arid to humid, depending on location. Generally, the closer an area is to the tropics, the stronger the influence of the subtropical high-pressure cells, and thus the drier the climate
marine west-coast climate
occurs in midlatitudewest coasts where prevailing westerlies bring moist air onshore from the adjacent oceans (latitude range 35° to 60° N and S). Precipitation comes mainly from low-pressure systems (where the coast is mountainous, annual precipitation is increased substantially by the orographic effect). Precipitation is plentiful in all months (often a distinct winter maximum).
In summer, the poleward extension of the subtropical high-pressure system leads to a reduction in rainfall. The annual temperature range is relatively small for midlatitudes (marine influence keeps winter temperatures mild, compared with inland locations at equivalent latitudes).
e dry midlatitude climate
at a latitude range of about 35° to 50° N, is limited almost exclusively to the interior regions of North America and Eurasia. Typically the region lies in the rain shadow of mountain ranges (maritime air masses are effectively blocked). In winter, the climate is dominated by cP air masses; in summer, a dry continental air mass of local origin is dominant. Summer rainfall is mostly convectional and is caused by occasional invasions of maritime air.
The temperature cycle is strongly developed, with a large annual range. Summers are warm to hot, followed by cold to very cold winters. Annual precipitation in the dry midlatitude climate is quite variable and there may be large differences in precipitation from year to year. Drought is an ever-present threat in the dry midlatitude climates, and its occurrence has serious implications for the region
moist continental climate
is restricted to the northern hemisphere, occurring at lat. 30° to 55° N in central and eastern parts of North America and Eurasia, and at lat. 45° to 60° N in Europe. These regions lie in the polar-front zone; seasonal temperature contrasts are strong, and day-to-day weather is highly variable. Ample precipitation throughout the year is increased in summer by invading mT air masses.
In winter, cold cP and cA air masses dominate these regions. The moist continental climate becomes progressively drier westward toward the continental interiors of North America and Asia
e high-latitude climate
re mainly restricted to the northern hemisphere. They occupy the northern subarctic and arctic latitude zones. Only the ice sheet climate of the polar zones is present in both hemispheres. The dynamic wind pattern at high latitudes brings mP air masses from the northern oceans into conflict with cP and cA air masses on the continents
The Rossby wave system transports lobes of warmer, moister air toward the poles in exchange for colder, drier air that moves toward the equator. The result of these processes is frequent wave cyclones produced along a discontinuous and constantly fluctuating arctic-frontal zone. In summer, tongues of mT air occasionally reach subarctic latitudes to interact with polar air masses and yield significant amounts of precipitation
he boreal forest climate
s a continental climate with long, bitterly cold winters and short, cool summers. The latitude range for this climate type is from 50° to 70° N. The boreal forest climate represents the source region for cool cP air masses, but invasions of cold, dry, stable cA air masses are frequent at these latitudes. The annual temperature range in the boreal forest climate is the largest of any climate type
The tundra climate
dominated by polar (cP, mP) and arctic (cA) air masses (winters are long and severe). The nearby oceans moderate winter temperatures, preventing from falling to the extreme lows found in the continental interior. There is a short mild season. Precipitation generally increases in the summer, when more moisture is available from the ice-free polar seas
Arctic tundra
rctic tundra lying beyond the arctic treeline describes both an environmental region and a type of vegetation dominated by herbaceous plants, such as grasses and sedges, together with mosses and lichens, and in some places small woody shrubs. The tundra is a treeless zone that borders the open lichen woodland at the extreme range of the boreal forest.
arctic Permafrost
Soils of the arctic tundra are poorly developed and consist of freshly broken mineral particles and varying amounts of partially decomposed plant matter (peat bogs are numerous). Because the soil remains permanently frozen not far below the surface, the summer thaw saturates the soil with water, especially in areas where drainage is limited by lack of slope (permafrost)
continuous permafront
which extends without gaps or interruptions under all surface features, coincides largely with the tundra climate
discontinuous permafrost
which occurs in patches separated by frost-free zones under lakes and river
