Transcript American Megafauna

Arizona Climate
Arizona Geography
GCU 221
Game Plan
1. Why is it so hot!
2. General Summer Circulation - Monsoons
3. General Winter Circulation - Cold Fronts
4. Phoenix Climagraph
5. Where do we get our water from?
1. Why is it so hot in Phoenix?
• Located in a sub-tropical high (clear skies)
• Located in the westerlies, down wind of the
Pacific ocean (keeps pressures high)
• Located downhill from mountains in California
(air warms adiabatically on the downhill
portion of mountains) keeping it dry
1. Sub-Tropical High
1. High Pressure
• Clear Skies, let’s in a lot of sunshine
• Descending air, very stable, low winds and low
circulation
1. Pacific High Pressure
1. Pacific High Pressure
1. Westerlies and the Pacific
1. Mountains and Adiabatics
1. Mountains and Adiabatics
2. Summer Monsoons
• Monsoon means a “change in the winds”
• Winds shift from “West” to “East”
• Azores High Pressure moves westward, driving
winds off the Gulf of Mexico and California
into Arizona.
2. Azores High Pressure
2. High Dew Points and Lifting
Mechanism
• Arizona’s monsoon starts when three days in a
row have dew points 55 degrees or higher.
• Moisture comes from the Gulf of Mexico and
Gulf of California.
• Lifting Mechanisms: Convection, Orographic,
Downdraft
• Need to lift the air to cool it and generate rain
2. Lifting Mechanisms: Convection
2. Lifting
Mechanisms:
Orographic
2. Lifting Mechanisms: Orographic
2. Lifting Mechanisms: Downdraft
3. Winter Frontal Systems
• Dominant air masses: Warm Moist to the
south Cold and Dry to the north
• Low pressures from the jet stream spin
counter-clockwise
• This forces the warm moist air over cold dry
air, causing storms
3. Winter Frontal Systems
3. Winter Frontal Systems
3. Winter Frontal Systems
4. Phoenix Climate graph
5. Arizona Watersheds
Major Water Sheds – Mogollon Rim, Colorado Rockies, Wind River
Mountains, and Utah Highlands
Major Rivers – Colorado River, Salt River, and Verde River
5. Arizona Water issues
5. Arizona Water issues
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Lowering groundwater table
Groundwater contamination
Lake Mead at low levels
Arizona watersheds not sufficient to support
Phoenix and sensitive to climate change
Things to know:
1. Why is it so hot!
2. Why do we get rain in the summer time?
3. Why do we get rain in the winter time?
4. Where do we get our water from , highlands and
rivers?
5. What are some issues facing our water supply
Help: Ask Dr. Douglass