Outline Further Reading: Chapter 11 of the text book - dry and moist subtropical climate regimes -...

Outline

Further Reading: Chapter 11 of the text book

- dry and moist subtropical climate regimes

- mediterranean regimes

- dry mid-latitude and moist continental regimes

Natural Environments: The AtmosphereGE 101 – Spring 2007

Boston University

Myneni L25: Mid Latitude Climates

Apr-23-07(1 of 16)

- marine west coast regimes

Introduction


Boston University


Apr-23-07(2 of 16)

• Previously,

– We looked at low-latitude climates

– Tend to be uniformly warm

– Principally differentiated by variations in precipitation

• Today,

– We shall look at the mid-latitude climates

– As opposed to low-latitude climates these climate regimes are differentiated by their temperature characteristics as well as their precipitation characteristics

Mid Latitude Climatic Regimes


Boston University


Apr-23-07(3 of 16)

– Climates located between 25N-55N (mostly in the Northern Hemisphere -> not much land mass in these latitudes in the SH)

– Influenced by• Pressure and wind systems

– Northern zone of subtropical high– Polar front

• Synoptic changes in Air Masses and fronts– mT, mP, cP– Traveling cyclones

• Strong seasonality in insolation• Seasonality in pressure systems

– Land-sea temperature differences– Cyclone formation and movement

– Produces 6 different climate regimes

1. Dry Subtropical Regime2. Moist Subtropical Regime3. Mediterranean Regime

4. Marine West Coast Regime5. Dry Mid-latitude6. Moist Continental

Dry Subtropical Climates-1


Boston University


Apr-23-07(4 of 16)

Subtropical High

Subtropical High

Pole-ward extension of Dry Tropical regime (25-35N) withslightly higher seasonality in temperature and precipitation

Dry Subtropical Climates-2


Boston University


Apr-23-07(5 of 16)

– Seasonality in temperature due to changes in insolation

– There is also some seasonality in precipitation due to the wintertime influence of midlatitude cyclones

– Vegetation consists typically of drought-resistant species such as cactus

(Yuma, Arizona)

Moist Subtropical Climates-1


Boston University


Apr-23-07(6 of 16)

H

Jet Stream

– Eastern subtropical regions

– Have consistent high humidity due to mT air from the western edge of the subtropical high

– In the summer there is also the influence of tropical cyclones

Moist Subtropical Climates-2


Boston University


Apr-23-07(7 of 16)

– Seasonality in temperature due to changes in insolation - typically hot summers; winters are cooler with the occasional incursion of cP air which leads to freezes

– Precipitation due mainly to convective activity in the summer and from midlatitude cyclones in the winter

– Vegetation is adapted to lots of water, such as mangrove swamps, etc.

Charleston, S. Carolina

Mediterranean Climates-1


Boston University


Apr-23-07(8 of 16)

H

Jet Stream

H

Jet Stream

– West coast of continents (between dry subtropical and marine west coast)

– In the summer, the region is under the influence of the subtropical high -> dry, clear, warm; influencd by mT, cT air

– In winter, the subtropical high moves south, region receives incursions of mP air, midlatitude cyclones which brings precipitation

Mediterranean Climates-2


Boston University


Apr-23-07(9 of 16)

• Temperatures are typically mild throughout the year due to the influence of the ocean, low latitudes (compared with other mid-latitude regions)

• Vegetation typically is drought resistant, also usually fire-adapted

Monterey, California

Maritime West Coast Climates-1


Boston University


Apr-23-07(10 of 16)

H

Jet StreamH

– West coast of continents at higher latitudes

– Fairly persistent precipitation all year long

• In winter, region is affected by mid-latitude cyclones

• In the summer, circulation around the subtropical high results in orographic lifting as westerlies move on shore

Maritime West Coast Climates-2


Boston University


Apr-23-07(11 of 16)

– Temperatures are typically mild throughout the year due to the influence of the ocean

– Regions of high productivity

– Dense forests in North America (old growth rainforests)

– Agricultural centers of Europe

Vancouver, BC

Dry Mid-latitude Climates-1


Boston University


Apr-23-07(12 of 16)

cT

cP– Continental interiors at mid-latitudes– Low annual precipitation

• Westerlies flow over mountain ranges, producing strong rainshadows• In N. America, region stretches from the Great Basin to the Great Plains

– Strong seasonality in temperature• Due to changes in insolation• Also due to influence of continental air-masses

– Winter: cold, dry air associated with cP– Summer: hot, dry air associated with cT

Dry Mid-latitude Climates-2


Boston University


Apr-23-07(13 of 16)

– Any precipitation they do get is from passing midlatitude cyclones

– Vegetation is transitional between desert and forest -> grasslands

(Pueblo, Colorado)

Moist Continental Climates-1


Boston University


Apr-23-07(14 of 16)

cP

mTH

– Central and eastern portions of the continents

– Strong seasonality in temperature

• Due to changes in insolation

• Also due to influence of continental air-masses

– Winter: cold, dry air associated with cP

– Summer: hot, moist air associated with mT

– Typically high precipitation all year long, although variable from day to day

• Summer: rain associated with warm, moist mT air (usually also associated with passing fronts)

• Winter: rain associated with mid-latitude cyclones

Moist Continental Climates-2


Boston University


Apr-23-07(15 of 16)

– Note that precipitation decreases in the winter -> due to the fact that the cP air has less moisture in it

– Ample water supply -> forests

(Madison, WI)

Summary


Boston University


Apr-23-07(16 of 16)

• Climate dominated by several factors– Latitude -> determines seasonality in temperature, precipitation

– Continental v. marine• Seasonality in temperature

• Availability of moisture

– East coast v. west coast• Interaction of the prevailing winds with land masses

• Impact of circulation around the subtropical highs

– Topography• Creates orographic lifting, rainshadows

Outline Further Reading: Chapter 11 of the text book - dry and moist subtropical climate regimes -...

Documents

Transcript of Outline Further Reading: Chapter 11 of the text book - dry and moist subtropical climate regimes -...