Weather Blog

Welcome summer! Enjoy the (extra) sunshine!

Welcome summer! Enjoy the (extra) sunshine!
Summer begins today at 4:59 p.m., and I'm sure many people have been counting the minutes. 

Mother Nature was celebrating with what is expected to be the warmest and sunniest day since our mini-heat wave in mid-May, with temperatures across the main Puget Sound area reaching into the 80s today (Seattle hit 83!). (The coast and North Interior will still be in the 60s, but, baby steps.)

To wit, it was just as warm in Seattle at 9 a.m. today (61) as it was for the entire day on Wednesday.

And happier news for sun fans, long range models have gone a little warmer for next week, with highs expected around 70 as opposed to 63-65.  This will make for a compelling race to see if we get enough warm days next week to thwart our attempt at making this the coldest June ever.

But with the summer solstice comes two questions we get a lot, so what better use of the blog than to answer them? Why is it the longest day of the year?

Most know the answer to this -- the earth is on an axis, and as we orbit around the sun, it's summer when the earth's axis is tilted most toward the sun, and winter solstice when it's tilted away.  The seasons are opposite between the northern and southern hemisphere because when the northern hemisphere is tilted most toward the sun (today), the southern hemisphere is tilted most away.

I didn't want to spend too much time here on that specific explanation, so for more information, check out this link:

http://www.wrh.noaa.gov/fgz/science/season.php?wfo=fgz

(Just don't read that part about standing up the egg on the equinox. I'm planning on writing something up on that this September, so don't be spoiled :) )

Of more interest to me is actual sunrise/sunset times on this date and some very unusual cases around the U.S. as the farther you go toward the poles, the more dramatic the difference in daylight between summer and winter solstice.

Seattle, by virtue of our northern location, has the longest daylight of major cities in the lower 48 -- the sun rises at 5:10 a.m. and doesn't officially set until 9:11, although twilight stretches a good 60-90 minutes beyond on a clear day.

To compare, down in Phoenix, the sun rises at 5:19 a.m., but sets at 7:42 p.m. (a little weird to compare to Seattle because Arizona does not observe Daylight Savings Time)

But go far to our north instead, and it gets amazing. Fairbanks, Alaska gets about 2 hours of darkness these days -- the sun sets just before midnight and rises again around 2 a.m.

Even better yet? Try Barrow, Alaska. Back on May 10th, the sun rose at 1:48 a.m.... and hasn't set since. The sun stays above the horizon, 24/7 until 12:53 a.m. on August 2nd.  The sun then races toward the other way, and by the equinox, the length of day is shrinking 9-10 minutes a day. (So, within a week, there's one less hour of daylight).

Finally, on November 19th, the sun rises at 12:52 p.m., sets at 1:32 p.m., and then is not seen again until January 23rd. Makes that 10:30 p.m. twilight not seem so jarring down here.

But there are other factors in play besides your latitude. For example, Seattle's sunset tonight is 9:11, but Spokane, which is on our same latitude, is 8:51 p.m.  Same goes for sunrise: Spokane is 4:52 am, Seattle is 5:11 am.

Here we find the other factor in play: Time zones. We cut up the planet into 24 time zones so everyone has the highest sun somewhere close to noon on our local clock (or, 1 p.m. now since we mess with this by going on Daylight Savings Time).

But the Earth doesn't play that way -- if we wanted to do this to where the sun is always highest at exactly noon, we'd need to cut the time zones up into much smaller pieces -- probably into 1,440 chunks to where it's based on minutes instead of hours.

That's way too confusing, of course, but even though Seattle and Spokane are in the same time zone, Spokane is roughly 20 minutes earlier than we are since they are farther east, and thus get the sunrise and sunset earlier.  If we really wanted to be precise, Spokane's clocks should be 20 minutes ahead of Seattle's.

Twenty minutes isn't significant, but go to Great Falls, Montana, and they are 44 minutes earlier than Seattle.  That's why they are in the Mountain Time Zone and why it's an hour later, to book-end the sunrise and sunset as much as possible around solar noon (the point where the sun is highest in the sky).

(Note that the "perfect" place to be exactly aligned around solar noon in the Pacific Time Zone is 120 degrees west longitude, or about the midpoint between Seattle and Spokane. Today, solar noon in Seattle is actually around 12:11 p.m. on Pacific standard time (or 1:11 p.m. on PDT) , while in Spokane, it's at 11:51 a.m. PST (12:51 p.m. PDT.) And yes, I get paid by use of the parenthesis.)

But want something *really* confusing, check out Indiana, where time zones change from county to county and year to year between Eastern and Central time. Their problem is that you have part of the state wanting to align with Chicago time (CDT) in the northwest, and part wanting to align with Cincinnati in the southeast (EDT) and Evansville in the southwest wanting to stay aligned with CDT for their neighbors in eastern Illinois, and some counties literally voting to change to one time zone one year, only to change their mind and go back the next year as residents square off whether it's best to align with Illinois or Indianapolis  -- it's all one big mess. (I'll bet the Dept. of Transportation, which is the official keeper of time zones in the U.S., doesn't even return their calls anymore.) And it was even more confusing when some of the state didn't observe Daylight Saving Time, but in 2005, they at least all decided to start observing it.

If you have some spare time, check out this article by Wikipedia:
http://en.wikipedia.org/wiki/Time_in_Indiana#Controversy

The connection to my blog is, by really messing around with geography and artificially forcing your town into other time zones, some places don't see a "noon" sun until after 2 p.m.

OK, your brain probably hurts now. He's something a little less brainy:

Why Isn't This The Hottest Time Of The Year?

The folks at SeaFair have done their homework. They picked the statistical driest and warmest time of the year for the annual event. But here it is the first day of summer, and the Blue Angels and hydros are nowhere to be found?

That's because the warmest and driest time of the year here is the last week in July and first week in August. (Cool chart to see for yourself, and do some long range planning here:

http://www.komonews.com/weather/faq/4308877.html )

Why the delay? Much like how water doesn't boil the instant you turn on the heat, the atmosphere takes about 30 days to fully transfer the heat from the greater amount of sunshine.

Conversely, the coldest time of year is statistically late January  for the same reason.  So there is always about a month's lag-time between the intensity of the sun and its effect on our climate.

The oceans are a bit longer -- about three months' lag time as water takes longer to warm. So the warmest ocean waters are typically in September and the coldest time is in March.  That's why the peak of hurricane season is in September and October -- it's when the ocean waters are warmest in the Atlantic and Gulf of Mexico.

But in the interim, enjoy the 70s today and sun fans can take note that the warmest weather is yet to come.