Chapter 7: Climates

narrow coastal belts of high rainfall, extend from near the equator to latitudes of about 25° to 30° N and S on the eastern sides of every continent or large island; The rainfall is supplied by moist mT air masses from warm oceans that are brought over the land by the trade winds and encounter coastal hills and mountains, producing heaving orographic rainfall

Trade-wind coasts

lying approximately on the Tropics of Cancer & Capricorn; hot barren deserts with little rainfall; They are located under the large, stationary subtropical cells of high pressure, in which the subsiding cT air mass is adiabatically warmed and dried

Tropical deserts

(high latitude); Found in latitudes of 60° to 75° N and S, except for the northern coast of Greenland, where it occurs at lat. greater than 80° N; Occupies arctic coastal fringes, and is dominated by polar (cP, mP) and arctic (cA) air masses; Climate is very COLD with Winters being long and severe; There is a very short mild season that provides a few months of thaw; Soil water is solidly and permanently frozen, this perennially frozen ground, or permafrost, prevails over the tundra region; Total annual precipitation is small

Tundra Climate

(low latitude); ITCZ; mE and mT air masses; Uniform warm temperature; Ample precipitation

WET EQUATORIAL CLIMATE

(low-latitude); Warm; Wide temperature range; Precipitation...; ITCZ=heavy rain; Subtropical high=dry

WET-DRY TROPICAL CLIMATE

(low latitude); Lies between 10° N and 10° S; Controlled by the ITCZ and is dominated by warm moist tropical and equatorial maritime air masses yielding abundant convective rainfall year round; Exposed to the tropical easterly trade winds; Temperatures are uniform throughout the year; Seasonal rainfall patterns, with heavier rain when the ITCZ migrates into the region

Wet Equatorial climate

heavy rainfall, straddles the Equator; In this zone, the warm temperatures and high-moisture content of the mE air masses favor abundant convective rainfall

Wet equatorial belt

(low latitude); Lies between 5° and 20° N and S in Africa and the Americas, & between 10° and 30° N in Asia; Very dry season alternating with a very wet season; Large annual differences in rainfall; Vegetation must survive alternating season of very dry and very wet weather; This situation produces a savanna environment of sparse vegetation; A typical vegetation cover in this climate is savanna woodland, a sparse cover of trees over grassland

Wet-Dry Tropical Climate

Low-Sun = very dry season Equatorial trough is far away, dry continental tropical (cT) air masses prevail; High-Sun = very wet season ITCZ is nearby, the climate is dominated by moist maritime tropical (mT) and maritime equatorial (mE) air masses

Wet-Dry Tropical Climate

alternate between wet & dry states

Wet-dry climates

An ____ ______ is classified according to the general latitude of its source region, which determines the temperature of the air mass and its surface type -land or ocean- within that region, which controls the moisture content

air mass

(climate factor); Colder regions generally have LOWER precipitation than warmer regions because warm air can contain more moisture than cold air; Precipitation will tend to be GREATER during the warmer months of the temp cycle

annual and monthly air temperatures

Climate is the ______ weather of a region

average

______ controls include altitude, elevation, and proximity to oceans.

climate

(climate factor); high-______ stations = cooler temperatures; atmosphere cools with the ________ at the lapse rate

elevation

(climate factor); The annual cycle of temperature at any place depends on its ________; Near equator = warmer temps & annual range is low Toward poles = cooler temps & annual range is greater

latitude

Insolation varies with ________.

latitude

Primary driving force for weather is the flow of ______ _______ received by the Earth and atmosphere

solar energy

The term ______ describes both an environmental region and a major class of vegetation.

tundra

Uniformly distributed; Summer, high-Sun maximum (insolation is higher); Winter, low-Sun maximum (daily insolation is lower)

3 patterns of monthly precipitation

(climate factor); Air masses that come from continental regions are DRIER while air masses that come from marine locations are MOISTER & can support more precipitation; In regions where two prevailing air masses collide, fronts will form, which can lead to precipitation

Air masses

precipitation remains low because air temperatures are low, and only a small amount of moisture is contained in cold air

Artic Zone:

northward of the 60th parallel, annual precipitation is small; Cold cP and cA air masses cannot contain much moisture, and do not yield large amounts of precipitation

Artic and polar deserts:

(high latitude); Long cold winter and Short cool summer; Large annual temperature range; Continental Polar; Precipitation=low total annual, but a Summer max.

BOREAL CLIMATE

(high latitude); Ranging from 50° to 70° N latitude; The annual range of temperature is greater than that of any other climate; Short, cool summers and Long cold winters; Occupies the source region for continental polar (cP) air masses, which are cold, dry and stable in the winter; Cold, dry continental arctic & polar air masses dominate; Total annual precipitation is small; Summer (max): occasional maritime air masses provide moisture for precipitation

Boreal Climate

a handy pictorial device that shows the annual cycles of monthly mean air temperature and monthly mean precipitation for a location, along with other things

Climograph

(climate factor); Ocean surface temperatures vary less with the season than land surface temperatures; Coastal regions show a SMALLER annual variation in temperature; Continental locations have a LARGER annual variation in temperature

Coastal-continental location

Continental interior regions; Rainshadow=dry air masses; Wide temperature range

DRY MIDLATITUDE CLIMATE

(midlatitude); Poleward extension of dry tropical; Higher latitude = a smaller/cooler temperature range, Cool Season, and Infrequent precipitation

DRY SUBTROPICAL CLIMATE

(low latitude); Subtropical high-pressure cell; very low precipitation; high temperature; deserts; Semiarid areas

DRY TROPICAL CLIMATE

Lies in lat of 35° to 55° N; Almost exclusively limited to the interior regions of North America and Eurasia, where it lies within the rain shadow of mountain ranges; The mountain ranges block the eastward flow of maritime air masses, and continental polar (cP) air masses dominate in the winter; Continental interiors in rain shadow or far from oceanic moisture sources; Precipitation is low

Dry Midlatitude Climate

The annual temperature cycle is strongly developed, with a large annual range; Summers are warm to hot, but winters are cold to very cold; True arid deserts and extensive areas of highlands can be found in the central portions of this region; The low precipitation and cold winters of this semiarid climate produce a steppe landscape dominated by hardy perennial short grasses

Dry Midlatitude Climate

(midlatitude); Found in a broad band of North Africa, connecting with the Near East; also found in Southern Africa and Southern Australia; Is a poleward extension of the dry tropical climate, but the annual temperature range is greater for this climate; COOLER temperatures during the low-Sun season because continental polar air masses invade the region; Midlatitude cyclones occasionally move into the subtropical zone in the low-Sun season, producing precipitation (infrequent precipitation)

Dry Subtropical Climate

(low latitude); Nearly all lie between lat. 15° and 25° N and S; Found in the center and east sides of the subtropical high pressure cell; Rainfall is rare; The driest areas are near the Tropics of Cancer and Capricorn

Dry Tropical Climate

Skies are clear mostly, so the Sun heats the surface intensely, keeping air temperatures high (daily temp range is large); Temperatures are HOT during high-Sun season; Temperatures are COOLER during low-Sun season; Semiarid steppes bordering many of the world's deserts often support nomadic grazing cultures; Typically have a short wet season that supports the growth of grasses

Dry Tropical Climate

are those in which total annual evaporation of moisture from the soil and from plant foliage exceeds annual precipitation by a wide margin; Generally do not support permanently flowing streams; Lacks plant cover

Dry climates

Wet Equatorial Asiatic Monsoon Wet-Dry Tropical Tropical Desert

Equatorial & Tropical Zones

a wet band stretching across the continent; this band is produced by convective precipitation over the equatorial lows near the intertropical convergence zone; Region is kept moist by the influence of the trade winds, which move warm, moist mT air masses and tropical cyclones westward onto the continental coast

Equatorial Zone

Westerly wind belt, warm moist tropical air; Cold polar air; Rossby waves; Wave cyclones

HIGH LATITUDE CLIMATES

The Boreal Forest Climate The Tundra Climate The Ice Sheet Climate

HIGH-LATITUDE CLIMATES (Group 3)

Cool to cold; Moist climates; Location = mountains and high plateaus

HIGHLAND CLIMATE

(Group 3): are climates of the northern hemisphere, and are dominated by polar and arctic (including antarctic) air masses; These climates coincide closely with the belt of prevailing westerly winds that circles each pole (Rossby waves); Jet stream disturbances form in the westerly flow, bringing pools of warmer, moister air poleward into the region in exchange for colder, drier air that is pushed equatorward; As a result, wave cyclones are frequent

High Latitude Climates

(precipitation patterns); east and west coasts have higher precipitation, while continental interiors and arctic and polar regions are drier.

Higher latitudes

Mountains & High plateaus; Cool to cold because air temperatures in the atmosphere decrease with altitude; Moist, wetter at higher locations as orographic precipitation increases; Generally derive their annual temperature cycle and the times of their wet and dry seasons from the climate of the surrounding lowland

Highland Climate

(high latitude); Arctic/Antarctic source region; Location = Greenland, Antarctica, and Arctic ocean ice; No month mean above freezing; Very low precipitation

ICE SHEET CLIMATE

(high latitude); Lies in lat. range of 65° to 90° N and S; It coincides with the source regions of arctic (a) and antarctic (AA) masses; Are situated on the vast, high ice sheets of Greenland and Antarctica and over polar sea ice of the Arctic Ocean; Annual mean temperatures are the lowest on Earth with no month having temperatures above freezing; Strong cyclones with blizzard winds are frequent, but precipitation, almost all occurring as snow, is very low

Ice Sheet Climate

lines drawn through all points having the same annual precipitation

Isohyets

system of letters to label climates; Classification is based on (1) Mean annual values of temperature (2) Mean annual values of precipitation (3) Season of highest precipitation (high-sun, low-sun) (4) Precipitation of the driest month

Köppen system

Location = Equatorial, Tropical, and Subtropical; Wet-dry; Influences = ITCZ, Tropical easterlies, and Subtropical highs; Weather = Easterly waves and Tropical cyclones

LOW LATITUDE CLIMATES

Wet Equatorial Climate The Monsoon & Trade-Wind Coastal Climate The Wet-Dry Tropical Climate The Dry Tropical Climate

LOW-LATITUDE CLIMATES (Group 1)

(Group 1) is dominated by the source regions of continental tropical (cT), maritime tropical (mT), and maritime equatorial (mE) air masses

Low Latitude climates

For the most part lie between the Tropics of Cancer and Capricorn; Occupying all of the equatorial zone (10° N to 10° S); Most of the tropical zone (10-15° N and S); Part of the subtropical zone

Low Latitude climates

Influences: two subtropical high-pressure belts and the equatorial trough at the intertropical convergence zone (ITCZ); The belt of tropical easterlies (NE and SE trades), and large portions of the oceanic subtropical high-pressure belt; Easterly waves and tropical cyclones are important weather systems in this climate group

Low Latitude climates

(precipitation patterns); annual rainfall is heavy in the wet equatorial belt and trade-wind coasts; In contrast, tropical deserts are very dry

Low latitudes

(midlatitude); Temperature=mild and small range; Precipitation=year-round, summer reduced

MARINE WEST COAST CLIMATE

(midlatitude); Narrow coastal zones; Summer=Dry and Winter=Wet; Moderate temperature range

MEDITERRANEAN CLIMATE

Location = All midlatitude, part subtropics, poleward- sub arctic, and N. Hemisphere; Influences = Poleward Subtropical High, Westerlies, and Polar front; Weather = Traveling cyclones, Anticyclones, Frontal boundaries, and Strong annual variations

MIDLATITUDE CLIMATES

The Dry Subtropical Climate The Moist Subtropical Climate The Mediterranean Climate The Marine West-Coast Climate The Dry Midlatitude Climate The Moist Continental Climate

MIDLATITUDE CLIMATES (Group 2)

(midlatitude); Temperature variation=large seasonal and strong day-to-day; Ample precipitation= summer peak and winter low

MOIST CONTINENTAL CLIMATE

(midlatitude); Warm moist air; Subtropical high; Eastern side of continent; Abundant rainfall

MOIST SUBTROPICAL CLIMATE

(low latitude); Heavy rainfall; strong seasonal patterns; larger temperature range; produces rain forests; ITCZ

MONSOON/TRADE WIND COASTAL CLIMATE

(midlatitude); Generally found in lat. 35° to 60° N and S; Receives the prevailing westerlies from a large ocean, and there are frequent cyclonic storms involving cool, moist mP air masses; When the coast is mountainous, annual precipitation is enhanced by the orographic effect; Precipitation is plentiful in all months, but there is often a distinct winter maximum; Summers are drier as subtropical high pressure moves poleward, blocking storm tracks; The annual temperature range is comparatively small for midlatitudes

Marine West Coast Climate

(midlatitude); Found between lat. 30° and 45° N and S; Along midlatitude west coasts; Has a wet winter and a very dry summer; DRY summer = Dry subtropical high pressure blocks rainfall; WET winter = The moist mP air mass invades with cyclonic storms and generates ample rainfall

Mediterranean Climate

Has arid to humid climates, depending on the location Closer to the tropics = stronger influence of the subtropical high pressure = drier climates Vegetation is adapted to survive through the long summer droughts Shrubs and trees are typically equipped with small, hard, or thick leaves that resist water loss through transpiration (Sclerophylls)

Mediterranean Climate

(Group 2) lies in the polar front zone- a zone of intense interaction between unlike air masses; ALMOST ALL ARE IN THE NORTHERN HEMISPHERE; Almost fully occupy the land areas of the midlatitude zone and a large proportion of the subtropical latitude zone; Also extend into the subarctic latitude zone

Midlatitude Climates

Influences= In this zone, tropical air masses moving poleward and polar air masses moving equatorward are in contact; Include the poleward halves of the great subtropical high-pressure systems and much of the belt of prevailing westerly winds; Tongues of maritime tropical (mT) air masses enter the midlatitude zone from the subtropical zone, where they meet and conflict with tongues of maritime polar (mP) and continental polar (cP) air masses along the polar-front zone

Midlatitude Climates

humid conditions continue along the east coasts; Subtropical high-pressure cells tend to move mT air masses from the southeast onto the continent in the summer, whereas in the winter, cyclones bring cyclonic precipitation from the west

Midlatitude Zone

between latitude 30° and 50°, are the great deserts as well as vast expanses of semiarid grasslands known as steppes; Located in regions of prevailing westerly winds, and typically lie in rain shadows on the lee side of coastal mountain and highlands

Midlatitude deserts and steppes

lying between latitudes about 35° and 65° in the region of prevailing westerly winds; In these zones, abundant orographic precipitation occurs as a result of forced uplift of mP air masses

Midlatitude west coasts

Moderating effect persists at every latitude. Temperature will be more constant with a slight seasonal variation

Moderating effects of maritime location

(midlatitude); Is restricted to the northern hemisphere between lat. 30° and 55° N in North America and Asia, and in lat. 45° to 60° N in Europe; Located in the polar-front zone (the battleground of polar and tropical air masses); Weather is highly variable; Seasonal temperature contrasts are strong, and day-to-day weather is highly variable; Large temperature range

Moist Continental Climate

Frontal precipitation is enhanced in summer by maritime tropical air masses; Summer = maximum precipitation; Winter temperatures are below freezing (snow is what is for LOW precipitation); Cold winters are dominated by continental polar (cP) and continental arctic (cA) air masses from subarctic source regions; Forests are the dominant natural vegetation cover throughout most of this climate

Moist Continental Climate

(midlatitude); Found on the eastern sides of continents between lat. 20° and 35° N and S; Eastern sides of continents in the Midlatitudes; Circulation around subtropical high-pressure cells provides a flow of warm, moist air; This flow of maritime tropical (mT) air dominates this climate

Moist Subtropical Climate

Abundant precipitation in the summer, much of which is convective; Occasional tropical cyclones add to this summer precipitation; Summer: warm, moist, maritime tropical air masses provide convective showers; Winter: midlatitude cyclones provide rain and occasional snow

Moist Subtropical Climate

are those with sufficient rainfall to maintain the soil in a moist condition through much of the year and to sustain the year-round flow of the larger streams; Support forests of many types of prairies of dense, tall grasses

Moist climates

located on the southeastern sides of the continents of North America and Asia, in latitude 25° to 45° N; These regions are positioned on the moist western side of the oceanic subtropical high-pressure circulations, which bring moist mT air masses from the tropical ocean onto the continent

Moist subtropical regions

(low latitude); Lies between 5° and 25° N and S; Wet periods (abundant rainfall); Easterly trade winds Annual cycle, small annual range, cooling during rains; Temperatures are warm throughout the year (large temp range); High-Sun = warmest temperatures; Low-Sun = coolest temperatures *creates the low-latitude rainforest*

Monsoon/Trade Wind Coastal climate

In high-Sun season, the ITCZ is nearby, so monthly rainfall is greater In the low-Sun season, the ITCZ has migrated to the other hemisphere, and the region is dominated by the subtropical high pressure, so there is less monthly rainfall; In the wet periods of this climate, equatorial east coasts receive warm, moist air masses from easterly trades, while tropical south and west coasts receive moist air from southwesterly monsoon winds

Monsoon/Trade Wind Coastal climate

(climate factor); Location on a mountain can greatly affect the amount of precipitation; On the WINDWARD side, the forced uplift of air over the mountain produces condensation and precipitation; On the LEEWARD side, adiabatic warming of the air produces hot, dry conditions

Mountain Barriers

(climate factor); Precipitation is affected by surface pressure patterns In the tropics & midlatitudes, LOW-pressures at the surface produce CONVERGENCE and lifting of air the SUPPORT precipitation; Over the subtropics & polar regions, persistent HIGH-pressure patterns produce DIVERGENCE of air and descent that INHIBIT the formation of precipitation

Persistent high- and low-pressure centers

At low latitudes, annual rainfall is heavy in the wet equatorial belt and trade-wind coasts; At higher latitudes, east and west coasts have higher precipitation

Precipitation; climate

is also affected by annual and monthly air temperatures, prevailing air masses, relation to mountain barriers, position of persistent high- and low-pressure centers, and prevailing wind and ocean currents

Precipitation; climate

(climate factor); On the WESTERN portion of midlatitude continents, the prevailing westerly winds bring warm, moist air off the ocean and onto the continent which = higher precipitation; On the EASTERN portion of midlatitude continents, the prevailing westerly winds bring dry air from the continental locations without enough moisture to produce signification precipitation

Prevailing wind and ocean currents

Moist subtropical Moist continental Mediterranean Marine West Coast

Subtropical and Midlatitude Zones

(high latitude); Arctic coastal areas; Long severe winter; Small temperature range; Moderating Ocean

TUNDRA CLIMATE

(1) Annual variation in insolation, determined by latitude, provides the basic control on temperature (2) the effect of location - maritime or continental - moderates that variation

Temperature Regimes

High-elevation stations show cooler temperatures than sea-level stations

Temperature Regimes

The contrast in temperature with season at a location depends on Latitude, Location, and Elevation; At higher latitudes, in continental interiors, and at higher elevations, the contrast is greater In continental interiors, there are large annual variations in mean monthly temperature and extremes in each season.

Temperature Regimes

Ocean surface temperatures vary less with the season than land surface temperatures, so.... Coastal regions show a SMALLER annual variation in temperature; Continental locations have a LARGER annual variation in temperature

Temperature; continental vs. coastal

Lower elevation = warmer temperature; Higher elevation = cooler temperature; The atmosphere cools with elevation at the average environmental lapse rate of -3.59°F / 1000ft

Temperature; elevation

The annual cycle of temperature depends on its latitude; near equator = annual range is low, and temperatures are warmer; towards poles = annual range is greater and temperatures are colder

Temperature; latitude