intro to geography: climate

Climate

Weather vs. Climate

• Weather- The day to day changes in atmospheric conditions for a location– Its snowing in Charlotte or it is hot and dry in Seattle– Studied by a meteorologist

• Climate- The long term (average) weather for a region – The climate in the Caribbean is generally warm/sunny.– Studied by a climatologist

Classifying Climate

• Koppen System– Most widely used– Based on temperature and precipitation patterns– Correspond with vegetation regions– Includes 6 major climate categories

Koppen System

Based on temperature characteristics(A)humid tropical climates(C) humid mesothermal climates

-mild winter(D) humid microthermal climates

- severe winter(E) polar climates

Koppen System

Characteristically dry regions(B) Arid climates

desert climates- extremely aridsteppe climates- semiarid

Temperatures range from very hot to very cold.

Koppen System

(H) Highland climates– worlds mountainous regions– vegetation and climate vary rapidly with

elevation

World Climate Regions (Koppen)

World Vegetation Regions (biomes)

Humid Tropical Climates(A)

• Tropical Rainforest and Tropical Monsoon– High temperature and humidity– Frequent heavy rain– Massive vegetation growth

• Tropical Savanna Climate– High temperature– Less rain, transition zone

Humid Tropical Climates (A)

Arid Climates (B)

• Steppe Climate– Transitional between humid and deserts– “dry savanna”

• Desert Climate– Very dry– Amount of precipitation is less than half of potential ET– Greatest temperature ranges in the world!

– Result of precipitation effectiveness

Arid Climates (B)

Humid Mesothermal Climate (C)(mild winter)

• Mediterranean Climate– Warm/dry in summer and mild/wet in winter– Dry season in summer

• Humid Subtropical Climate– Mild winters and hot summers– No dry season (high humidity/ showers)

• Marine West Coast Climate– Temperate oceanic climate– Westerlies – Cloudy foggy and rainy

Humid Mesothermal Climate (C)

Humid Microthermal Climates (D)(severe winter)

• Humid Continental (hot summer)– Productive agriculturally– Climate classification for New Jersey!

• Humid Continental (mild summer)– Poleward of the hot summer regions (like New England)

• Subarctic climate– Short/cool summers and long/very cold winters– Permafrost- permanently frozen layer of subsoil

Humid Microthermal Climates (D)(severe winter)

Polar Climates (E)

• Tundra Climate– Close to the poles, avg. temp around 40 F– Treeless, low growing vegetation

• Ice-sheet climate– All average monthly temperatures below freezing– Precipitation limited to fine/dry snow

Polar Climates (E)

Highlands Climate (H)

• Based on elevation • High variability from hour to hour and place to

place

Highlands Climate (H)

• Tree Line- altitude above which low temperatures and severe wind limit growth of vegetation

• Snow Line- Where warmth of summer is not enough to melt snow from the previous year

Highlands Climate (H)

Climograph

• Plots average monthly temperature and rainfall

Climographs

Climate Factors

Climate Controls

• Latitude • Air circulation and pressure belts• Ocean currents • Altitude • Landform barriers • Human activity– Deforestation, increase of heat trapping gases

Latitude

• Less direct sunlight = cooler climate

Air Circulation

Three important things to remember!

• Warm air rises and cool air falls– result of density differences

• Wind always blows from high to low– result of pressure differences

• Warm air holds more moisture– When air cools moisture condenses to form rain

High and Low Pressure

• Cyclone- warm air converges and rises• Anticyclone- cool air sinks and diverges

Pressure Belts

Atmospheric Circulation

World Precipitation

Ocean Currents

• Oceans take longer to change temperature than air– It takes water longer to

warm up in the summer and longer to cool off in the winter

– Keeps the coast cool in the summer and warm in the winter

Ocean Currents

AltitudeTemperatures fall by 6 °C with every 1000 m gained in elevation

Landform Barriers

• Windward- facing the direction the wind is coming from

• Leeward- facing the direction the wind is blowing away from (sheltered)

Future Climate

Climate Change

• Global Warming- recent rise in atmospheric temperatures• 11 of 12 hottest years in recorded history have occurred since

1995

– What are the causes?– Natural or human related?

• Remember, correlation does not imply causation!

Hockey Stick Graph

Bigger Picture

Climate Change

Climate Change

Bigger Picture

Possible Causes

• Orbital variations– Milankovitch Cycles– variations in eccentricity, obliquity, and precession– Happens over thousands of years

Possible Causes

• Atmospheric changes– Change in composition of atmosphere– Increase in “greenhouse gases”– Volcanic activity

Possible Causes• Solar Activity• Sunspot cycle is 11 years from solar maximum

to solar minimum

Possible Causes

• Landmass changes– Plate tectonics/movement of land masses• continents in polar latitudes

• Impact events– Asteroids/comets– largest known-15 km diameter – “Impact winter”

Future Climates

• Hard to predict because of high variability• We know climate will change based on studies

of the past• We will most likely go through periods of

warming and cooling, just as in the past• Changes in human population and activity will

change our predictions.