So I found myself chuckling this morning because everyone here in LA is whining about how cold it is in the morning (temps in the 40s and 50s), and yet, the daytime highs have gotten up near 80. My initial thought was that the 35-40 degree change over the course of the day is a lot, but I quickly realized that we often get the same amount of change, just in a different range of temperatures, during the summer months.
So now I’m wondering what parts of the country, and then what parts of the world, experience the greatest degree <rimshot> of change on average during the course of a day. And is there a particular time of year when the amount of change is greater?
My guess is high-altitude equatorial deserts with clear skies and low humidity.
Deserts, to get away from the temperature-moderating influence of large bodies of water. Equatorial, so they get the intense sunlight during the day and heat up; high-altitude, low-humidity and clear, so they get clear non-obstructive skies at night and can easily radiate heat to the cold night sky.
For a limiting case of this, look at the temperature variations on the moon.
Not just to get away from the large water bodies (which do moderate temperature swings), but also to get away from much humidity in the air, which also does its thing for temperature moderation.
According to this site “Regions having the largest diurnal variation are generally deserts in the subtropical zones.”
And according to this one “Diurnal temperature variation is most pronounced around the equinox, when the differences in solar radiation from day to night are greatest.”
Or, what Sunspace said.
Diurnal shift is something that comes up often in my classes and Paso Robles is often touted as having the one of the greatest variations in the state and world as far as winegrowing regions go.
It has to do with the way the Santa Lucia Mountain ranges runs (East/West vs. North/South), the ‘Templeton Gap’, sea breezes, and the valley location. See here for a little more on that if you’re interested.
