May 28, 2009

90 (plus humidity)

Since the start of May, Phoenix Arizona has had 15 days rise above the 100º F mark.

Naples can only lay claim to two days above 90º F over the same period.

It’s obvious which is hotter … during the summer that is.



Come winter the temperature tables are reversed:

Daytime highs rarely drop below 70º F in Naples, whereas Phoenix can get downright nippy.



Monthly map of mean temperatures. Source: New, M., Lister, D., Hulme, M. and Makin, I., 2002: A high-resolution data set of surface climate over global land areas. Climate Research 21: 1–25

That summer-winter flip flop is explained by the difference in relative humidity.

In Naples you are unlikely to see relative humidity, as measured under the peak day sun, drop below 40 percent. The summer mid-day standard is 60 percent.

The standard in Phoenix is closer to 20 percent, and routinely below 10.



Thus, have a sweater on hand if you make a winter visit to Phoenix. And if you find yourself in Naples come summer time, you’ll want to turn the AC on most of all at night – not so much for the heat (which cool into the 70s), but for the humidity – which rises upwards of 90 percent.

3 comments:

Lou said...

So the question is--unrelenting heat or unrelenting humidity!

Janie said...

Ah, yes, that humidity is why I feel like I'm suffocating when I walk out of an airport in the south. Not used to any of that stuff here in Utah.

TROLL Y2K said...

I'd like to see a post on "Urban Heat Islands" and/or "Furnace Cities". Pretty sure it adds about 10 degrees to Phoenix and 15 degrees to some Asian mega-cities.