Wednesday, June 20, 2012

It Doesn't Get Any Higher In The Sky

Today marks the summer solstice -- the day when the sun's direct rays are pointed at the Tropic of Cancer and the Northern Hemisphere is at its most direct tilt towards the sun. The sun's height in the sky is as high today as it will get...from here through December, the Earth's tilt will take us away from the most direct light and lead us towards the winter solstice in six months time.

Today's fifteen hour length of daylight -- from sun-up at 5:36 this morning to sunset at 8:36 one of several days that have fifteen hours of daylight with them.  You'll get to enjoy those late sunsets for several more weeks before the creep of shorter sunsets really takes hold in August.

Around America, the length of day on the longest day of the year varies tremendously...all based on latitude. The tropical latitudes see little variation in day length through the course of the year so daylight length in Honolulu doesn't change much from December to June...only a matter of a bit more than two hours difference.  However, the mid and northern latitudes will vary much more widely.  Minneapolis's 15 hour and 37 minute day will whittle away to 8 hours and 46 minutes in six months...a difference of nearly seven hours. In Anchorage, December 20th will feature 5 hours and 27 minutes...a decrease of nearly 14 hours.  In Fairbanks, that decrease is over eighteen hours!

Philadelphia's shortest day brings 9 hours and 20 minutes of daylight, a decrease of just under six hours from today.  Of course, shorter days will gradually yield the potential for colder weather...many months from now...but it should provide some solace to those of us who weathered a rather hot day today.