01 August 2009

Monsoon in the Desert?

What exactly is a monsoon? It is a season of extremely heavy rainfall that lasts for months in India... so why am I mentioning it in the Mohave Desert in Arizona? 
When we first moved to Arizona, and lived in the Phoenix valley which is in the Sonoran Desert, the locals referred to the massive rainfall that happened in the late summer/early fall as their monsoon season. It thankfully only lasts for a few weeks there, but it is characterized by overwhelming amounts of water pouring out of the sky. 
The largest problem with this is that the ground in the desert is DRY. It is so dry that it can not absorb the water any where near as fast or in the amount of what is falling from the sky. When this happens, roads flood, houses flood, people get stranded... Think about trying to soak up a spill with a dry sponge. That is how the desert ground acts with the rainwater.
The next problem are washes. I first heard the term "wash" used to describe landscape living in Arizona. A wash is an area that becomes a river during heavy rainfall. These washes often cross roads, and are powerful enough to sweep a car driving down the road into the stream and off into the distant desert. When they are not filled with water, which is most of the year, washes are some of the most beautiful places to hike and explore. They are just filled with life!

As we are now in our second monsoon season for the Mohave Desert of Arizona, I now have quite a different view of the term "monsoon season". Where we live, it is a joke to my neighbors that we can see the rain, we can sometimes even walk to the rain, but we just do not get any rain here. Seriously, a downfall here is like a light sprinkle in Chicago.We run out to play in the rain every time it starts. It is so wonderful for the five to ten minutes that it lasts! 
I was chatting with my neighbor the other day and she mentioned that we were in the middle of monsoon season. That struck me as quite funny because we have only had one sprinkle this month. But I defer to her wisdom, as she has grown up here. I started thinking about the weather and what she had said, and that's when it occurred to me what the definition of monsoon season actually is here. Here it is the increase of humidity, with more rain than usual. Does that sound funny? 
Most of the year we enjoy a humidity of only 4% or 5%. It is quite dry. When rain does fall, it is evaporates in the air before it ever hits the ground. This dryness makes it SO much easier to handle the extreme heat. 105 degrees is really fairly comfortable at 5% humidity. At least it is once your body adjusts to it! But being monsoon season, we have been experiencing humidity in the range of 20% to 45%. The heat of 120 degrees at that humidity is totally unbearable... at least to me and the kids!
For most of you these low humidity ranges must sound ridiculous. I do understand. I grew up in Chicago, IL. I know what over 100% humidity feels like, even if I don't know how it can exist! I do remember the radio announcers in the summer saying it. Mostly I remember it being 96% humidity over the summer because that was the radio station I listened to in high school! 
So, now you know that deserts can be different from each other, and what a monsoon in the desert is!


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