Climate

Chapter 14

Climate

What is climate?

• What is the definition of climate from Chapter 12?– Long term variations in weather for an area

• What is climatology?– The study of Earth’s climate

Normals• Climate data is compiled

from meteorological records continuously. – This data is averaged on a

monthly or annual basis for 30 years to determine the normals.

– What is a normal?• Standard value for a location• Do not describe daily weather

conditions

Normals

What Causes Climate?1. Latitude: How would latitude

affect climate? Amount of solar radiation received

at any one place differs. What areas receive the most? Tropics

2. Topographic Effects Large bodies of water heat and cool

slowly What does this mean for costal

areas? Remain warmer in winter

What do you think mountain climates are like? Usually cooler due to higher elevation

Latitude

Topographic Effects

What Causes Climate?

3. Air Masses Areas where air masses form have similar climate

to the air mass itself

Climate Classification• Two Factors used:

1. Temperature2. Amount of Precipitation

• Koeppen classification system– Based on average monthly temp. and precipitation

values

Tropical Climates

• Constant high temperatures• Most have large amounts of rain– Some have dry winters (Savannas)

• Dramatic vegetation

Dry Climates

30% of Earth’s land area Largest climatic zone

Deserts Low precipitation Scarce vegetation Hot, tropical air

Mild Climates1. Humid Subtropical: SE United States

Subtropical high-pressure systems over oceans in summer

Warm, muggy weather during the summer

2. Marine West Coast: West United States Constant inland flow of air off ocean Mild winters, cool summers Abundant precipitation

3. Mediterranean: Italy and Spain Warm Summers

Continental Climate Three Zones

1. Warm Summer2. Cool Summer3. Subarctic

Clashing tropical and polar air masses What occurs when this happens?

Tornadoes

Rapid and violent changes in weather; extreme temperatures; A lot of precipitation in summer

Polar Climates

• Coldest regions on Earth• Precipitation is low• Heat radiation by Earth’s surface is low.– Too low to produce strong convection currents– What do convection currents produce?• Heavy precipitation

Microclimate

A localized climate that differs from the main regional climate

Heat Islands Buildings and concrete cause climate to be

warmer than surrounding rural areas Concrete radiates a lot of heat back in to the air

Heat islands

Ice Ages

Periods of extensive glacial coverage. Average global temperature decreases by 5°C Most recent ended about 10,000 years ago

Seasons: short-term periods of climatic change Caused by regular variations in daylight, temperature, and weather patterns.

• Tilt of Earth• Orbit of Earth• Amount of sunlight

Short-Term Climate Change:

Short-Term Climate Change El Nino: warm ocean current

Occasionally develops off South America Warms air on South American coast

Natural Climate Change• Solar Activity

Maunder minimum: low sunspot activity corresponds to unusually cold climatic episode

Earth’s Orbit: varies from circular to elliptical What do you think happens when the orbit goes from

circular to elliptical? Elliptical=Earth passes closer to the sun=warmer temps

Earth’s Wobble: Earth does not always point to the North Star which changes effects of seasons

Volcanoes: How would this affect climate? Volcanic ash can block solar radiation

Greenhouse Effect

Retention of heat by the atmosphere Keeps Earth from getting too

hot or too cold

Global warming: Theory that the release of too

much CO2 in the atmosphere is causing an increase in global temperatures

Deforestation contributes to global warming