"Summertime...."

Well, not yet, though ask anybody around here and they'll tell you 'summer' has been here for a while already. Nice to have the heat break, and while not drastically cooler, it is more fresh, and the lower humidity is appreciated.

The 2008 Summer Solstice takes place this Friday at 7:29 pm (which in Universal time is 1 minute before midnight starting at the Prime Meridian). At the June solstice it's only 'summer' in the northern hemisphere, of course, as the southern pole is pointing away from the sun and they are in their 'winter' in the southern half of the earth.

The sun will never set at the north pole on that day, and the sun's rays will be directly overhead along the Tropic of Cancer at 23.5 degrees latitude north (and to further brush out the brain's cobwebs, the earth's axis has a 23.5 degree tilt).

With the our summer solstice, you might think we should have our hottest temperatures since we have the most hours of daylight and the most direct sun rays. Alas, there are myriad other factors at work to produce 'heat', not just the sun angle and duration, though that certainly factors in.

In meteorology, we use the term "Lag of the Maximum" which basically covers the delayed response to temperatures compared to the origin of stimulus. It can be as simple as a daily 'lag' or a broader scale seasonal 'lag'.

On a daily scale, solar energy comes to earth in shortwave form, get's absorbed at the surface (or reflected back in some cases), and then that energy is sent back out in longwave form. It's the longwave form that gives us heat (or not if there is much reflectivity)...the 'Greenhouse Effect', in essence...that effect goes, though, goes one step further to talk about factors that keep the longwave radiation from disappearing out into space,keeping them in our earthly 'house', warming it up, just like a good ol' greenhouse does.

On a more seasonal scale, all weather is driven by the sun, at the very base level. The varying temperatures created make for various pressure differences, which creates rising and descending air, creating major air currents which help form jet streams, which help drive storm systems and even major ocean currents, and then the whole mix of geography and land-vs-sea borders...and I'll just stop there with candy-coating of an extremely complex but fascinating interplay of major weather systems and climate regimes.

Returning to the solstice idea of longest day and most direct sun rays, on a seasonal scale it takes a good month or two for the resulting weather patterns to respond to that stimulus, hence our hottest temperatures can occur long after the June solstice. That's not to say you can't and won't have oven-like temperatures around or before the summer solstice....uh, I think what we recently experienced was a little proof in the pudding...it's just that, statistically, it's less common than heat waves later in the summer.

And so in unrelated fashion except for the title of the song, I give you two links to two superb video versions of the "Porgy and Bess" classic "Summertime". Ella is Ella, what can you say...and Fantasia's performance in her American Idol unveil was overflowing the Spirit and energy and talent all musicians dream of producing. There are many other wonderful performances - these are but two goodies. Enjoy!

ELLA FITZGERALD
Berlin 1968

FANTASIA BARRINO
American Idol