Climate of the Southwestern US
Climate is a description of the average temperature, range of temperatures, humidity, precipitation, and other atmospheric/hydrospheric conditions a region experiences over a period of many years. These factors interact with and are influenced by other parts of the Earth system, including geology, geography, insolation, currents, and living things.
Because it is founded on statistics, climate can be a difficult concept to grasp, yet concrete examples can be illuminating. Terms like "desert," "rain forest," and "tundra" describe climates, and we have gained a general understanding of their meaning. Climate can also encompass the cyclical variations a region experiences; a region with a small temperature variation between winter and summer—San Francisco, for example—has a different climate from one that has a large variation, such as Buffalo. Scientists have settled on 30 years as the shortest amount of time over which climate can be defined, but it can of course also define time periods millions of years in length.
You cannot go outside and observe climate. Weather, on the other hand, can be observed instantly—it is 57 degrees and raining right now. Weather varies with the time of day, the season, multi-year cycles, etc., while climate encompasses those variations. Our choice of clothing in the morning is based on the weather, while the wardrobe in our closet is a reflection of climate. Due to the area's great regional variety, from the arid zones of the Basin and Range to the higher, wetter parts of the Rocky Mountains, residents of the Southwest have a diverse wardrobe. While the entire Southwest experiences seasonal variation, southernmost Arizona and New Mexico experience much less variation due to the warmth of their winters.