Deserts are places where there is not very much rain at all.  For example:

1. The Great Salt Lake Desert receives less than an average of 25cm of rain in a year.
2. The Gobi Desert receives less than an average of 25cm of rain yearly.
3. The Kara Kum Desert receives less than 25cm of rain a year.
4. The Atacama Desert receives less than 3cm of rain yearly.

 

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When it does rain, it makes BIG floods and animals and people die.  Some animals, like the Brine Shrimp can only breed in these wet times.  Some plants like Rosy Dock only grow in the rainy periods.

If my suburb only had that much rain for a long time, people would die because there would be no water to drink.  Animals and plants would also die.