A bucket about the weather (well actually climate). More below the blurb.
The Daily Bucket is a place where we post and exchange our observations about what is happening in the natural world in our neighborhoods. Birds, blooms, bugs & more - each note is a record that we can refer to in the future as we try to understand the patterns that are quietly unwinding around us.
I never really paid that much attention to weather patterns until I lived in Arizona. In the arid southwest every rainfall is an important event and you tend to notice the times of year when it tends to rain.
Within Arizona there are three main factors influencing the probability of rain: time of year, location in the state on an east/west axis, and elevation.
If you look at a map of the world that shows habitats deserts are usually shown in brown. You will see a lot of brown on the maps at approximately 30 degrees latitude both north (SW North America, Sahara, Middle East, Central Asia) and south (Namib and Kalahari, Australia, northern Chile) of the equator. Air rises in the equatorial regions (the sun is hot there and heats it up) and then moves north and south (has to go somewhere) as more air rises below it. The air cools and descends at about 30 degrees N and S. As it drops down it warms and can hold more moisture. Thus it tends dry out the environment at those latitudes.
Rainfall in the interior southwest is concentrated in two seasons. During winter, 'storms' off the Pacific sometimes reach the interior and bring widespread gentle rain. The summer is the monsoon season. Hot air rises, drawing in moister air from the south. There are frequent, local thunderstorms.
The effect of these seasons varies geographically. Western Arizona is primarily influenced by winter rain with summer storms being uncommon. Eastern Arizona has less winter rain and more summer rain.
The summer storms typically build up over mountains and then spread to the surrounding valleys. The summer rains start earlier in the mountains and tend to fall more regularly. In the desert valleys there are fewer storms but the ones that fall are often extremely powerful.
The pictures in this diary are off an early summer storm over Bryce Canyon National Park in Utah. This is the driest time of the year in the southwest. Precipitation is almost non-existent in May and June. This is the very start of the monsoon and rain is starting to fall but it is evaporating before it reaches the ground. We were at 9000 feet watching this. It got cloudy in the afternoon down lower but the rain only occurred over areas of high elevation.
Where I live now is almost exactly at 30 degrees N but the influence of the Gulf of Mexico ensures that Tallahassee does not have a desert climate. We do have a summer rainy season but even our driest times of year would be quite wet by Arizona standards. We have now had two whole days in a row without rain and the weather is warming up a bit.
That's it from me. What's going on where you are?
"Green Diary Rescue" is Back!
After a hiatus of over 1 1/2 years, Meteor Blades has revived his excellent series. As MB explained, this weekly diary is a "round-up with excerpts and links... of the hard work so many Kossacks put into bringing matters of environmental concern to the community... I'll be starting out with some commentary of my own on an issue related to the environment, a word I take in its broadest meaning."
"Green Diary Rescue" will be posted every Saturday at 1:00 pm Pacific Time on the Daily Kos front page.