Geography, Climate, Life Zones
The Sonoran Desert reaches from central Arizona down into Mexico and Baja, California. It is called the Sonoran Desert because much of it is located in the state of Sonora, Mexico.
The Sonoran Desert, a subtropical desert located in the Southwestern climatic zone, is the world's only desert with two "rainy seasons".
Brief, intense, compact, "monsoon" storms originate in the Gulf of Mexico andarrive from the south. Clouds like those pictured lower left build along the Mongolen Rim to the northeast. Tropical storm cells sweep across the desert. Often these storms are followed by a rainbow as shown in these photographs donated by volunteer Howard Meyers.Click on the pictures to enlarge them.
Storms last longer, cover more area, have gentle rain, originate in the Pacific Ocean and arrive from the north. These cloudy days are unusual here in the Valley of the Sun.
Annual Rainfall: 7" to 16.4"
January: 51.8 degrees F.
April: 65 "
October: 70.6 "
July: 85.9 "
Arizona's plant life spans six main life zones from a low point of 70 feet near Yuma to a high point of 12,670 feet in the San Francisco Peaks near Flagstaff. The Desert Foothills Scenic Drive is located in the Lower Sonoran Life Zone.
Willing to Wait
Spring annuals survive as seeds, some for decades. When temperatures are right and rainfall in the fall and winter (January and February) is sufficient, the seed germinate. These types of plants are referred to as ephemerals (of very short duration). They develop quickly, blossom and soon go to seed.
Many Survival Techniques
Paloverde, mesquite, ironwood, and bursage survive desert conditions because of their reduced leaf area. Others, such as the jojoba and creosote, have specialized leaves for desert survival, while the ocotillo shed all their leaves during periods of drought. Still others, such as the cacti (saguaro, barrel; etc.) and certain bushes, have vestigial leaves or have modified their leaves to spines over evolutionary time.
Arizona's Unmatched Diversity
The other five Arizona life zones support different types of plants. Visitors from New England and the Northwest will feel more at home in these area.
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