Climate: Causes and Classification

What is CLIMATE? Long-term weather patterns for an area (climatology) Variations in temperature, precipitation, and winds throughout the year

What causes CLIMATE? An area’s climate is caused by a combination of 4 factors: Latitude Topographic Effects Air masses Side of Mountain Range

1st Cause of Climate: Latitude Most important cause! The latitude (how far North or South of the equator) determines how much solar radiation an area receives due to Earth’s tilt Equator = little tilt = high direct sunlight Poles = high tilt = little direct sunlight

2nd Cause of Climate: Topographic Effects Land vs. Water (distance to water) Coastal areas = wetter and moderate temperatures Inland areas = drier and more extreme temperatures Elevation Mountains = cooler Lower elevations = warmer

3rd Cause of Climate: Air Masses Same types of air masses move into the same area at the same time each year Air masses bring the characteristics of their source regions (cP, mT, etc) Air masses moving in interact with the air masses present to influence climate

4th Cause of Climate: Side of Mountain Range Windward Side Moist air rises over a mountain & cools at the top Wet climate forms Leeward Side Cold, dry air sinks down from the mountain & warms at the bottom Dry/Desert climate forms

Koppen Classification System

Koppen Classification System Uses average monthly and annual values of temperature, precipitation, and vegetation to classify climates

Koppen Classification System Contains ~5 main divisions: Humid Tropical Dry Humid Mid-Latitude Continental Polar

Koppen Classification System: Humid Tropical Climates Constant high temperatures – no change in seasons Constant high humidity High amounts of precipitation Near the equator

Koppen Classification System: Dry Climates Little to no precipitation Hot summers & cool winters Subtypes: Arid (desert) Semi-arid

Koppen Classification System: Humid Mid-Latitude Climates Mild winters & warm, humid summers Abundant (lots of) rain Subtypes: Marine Humid subtropical Mediterranean

Koppen Classification System: Continental Severe winters & mild summers Primarily (mostly) located north of the equator Subtypes: Temperate Highlands

Koppen Classification System: Polar Climates Coldest regions on Earth (year-round) Little precipitation Winter days are (almost) all darkness; summer days (almost) all daylight Antarctica