I’ve written twice previously about time zones (Part 1, Part 2), which has catapulted my blog to the upper echelon of blogs written by chemistry professors leading study abroad programs in South America.  We’re talking top 3 or 4 for sure.  Like a dying movie studio, I keep going to the well trying to reel in the readers.

Today is a big day in Chile as the clock rolls back and we all get an extra hour of sleep.  It also puts sunrise and sunset at more reasonable times.  Today, the sun rose at 0730 and will set at 1754.  This contrasts with yesterday’s 0830 and 1954.  Sunrise well after 8am is hard to deal with.

I thought I was going to have a Part 4 to add in as I was initially told that Easter Island, where we were last week, was on the same time as Chile.  Which is on the same time as Argentina.  I thought this sounded ridiculous but didn’t do my due diligence.  It would have meant that Buenos Aires and Hanga Roa were on the same time despite being separated by nearly 40 degrees of longitude.  Of course, it didn’t turn out that  way at all.  The clocks in Easter Island are set two hours earlier than in Santiago, so they are effectively operating on Central Time.  Hanga Roa is at 109 degrees west longitude.  Or, rather, due south of the Four Corners area of the United States.  So they should really be on Mountain Time.  You could tell because sunrise in Hanga Roa did not take place until a quarter to nine in the morning.  (No, no pictures yet of Easter Island.  Killing you, isn’t it?)

In Chile, we switched off Daylight Savings Time (or, as it is called here, “Summer Time”) at midnight.  That is, we “fell back.”  Because it is Fall.  And it really is.  It’s cool and cloudy and there are lots and lots of wet leaves on the ground.  So, now that Santiago is not on Summer Time and the United States is on Daylight Savings Time, Santiago and Winston-Salem are on the same time.  Which is going to make it easy to know when to stream graduation tomorrow.

Mary and I rented a car for the weekend.  I had intended to take her out for a hike but we got a late start to Saturday due to the sun not rising until a few hours after we normally get up.  We finally stumbled out for a run (“we”! ha!) a little after 9am and so it wasn’t until after 11 when we got to the rental place and then there was a line which was handled with the normal Chilean efficiency.  So it was that it was after 1pm before we were off.  I decided a hike was likely not in order so I thought I’d show her the El Yeso reservoir where I’ve gone twice with students.

The drive was long, especially going in late afternoon rather than the usually much quieter morning.  Last time I was there I thought the snow on the mountains around the reservoir was new.  This time there was no question.  The last mile and a half to the reservoir was muddy and wet as snow melt streamed down the unpaved road.  We couldn’t get to the beach and definitely not to the national park a few miles beyond due to high snow.  But we did see the reservoir and take in some cold mountain air.  It was beautiful.

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The same view back in March.IMG_3484

Today, we’re stocking up the house and trying to plan the week’s activities and meals.  It’s a regular week for both of us: classes and work.

Back home, the class of 2017 is graduating tomorrow at 9am (Winston and Santiago, remember).  Congratulations to all of them.  It’s a class I feel particularly close to having lived in London with them for six weeks in 2014 and had 4 or 5 more work in my lab.  They’re a great bunch and I wish them the very best in their future and hope they keep in touch.

To close out the time zone discussion, I will again reference the sun.  As I wrote in Part 2, local noon is when the Sun crosses the meridian, when it is at its highest point in the day.  That happens at the same time for any given line of longitude.  The Sun is at its highest point for 109 degrees west no matter what latitude you’re on on that line.

But the height of the Sun does vary considerably.  The Sun, today, is at a declination of 18 degrees, 48 minutes north (18.8 degrees).  Which means it would be straight overhead, at noon, at a latitude of 18 degrees, 48 minutes north.  So, from Winston-Salem, at a latitude of 36 degrees north, the Sun, at noon, will be 17 degrees 12 minutes south of straight up.  The formula to figure out the angular altitude (how many degrees above the horizon the sun is) of the sun at local noon when the solar declination is in the same half of the sky as your latitude is:

                                 angular altitude = 90 – (local latitude – solar declination)

So, for Winston-Salem today, that is 90-(36-18.8) = 72.8 degrees.  If the solar declination is south of the local latitude, the sun will appear in the southern half of the sky.  This is true for Winston-Salem.

Here in Santiago, that bold caveat does not apply.  Here, our equation is:

angular altitude = 90 – (local latitude + solar declination)

Which gives us:  90-(33.5+18.8) = 37.7 degrees.  So, at local noon in Santiago, the Sun is only 37.7 degrees above the northern horizon.  At the winter solstice, the Sun will only be about 33 degrees above the horizon at noon while in Winston-Salem it will be nearly 78 degrees high.  You know this in your gut, the Sun is high in summer and low in winter.  The only real difference is that, here in Santiago, the Sun is in the northern half of the sky while in Winston, it is in the southern half.  Earth’s movement confines the Sun’s apparent location to between 23.5 degrees north and 23.5 degrees south.  So, to see the Sun from Winston, you must always look south and to see it from Santiago you must always look north.

So, there you go.  Three posts on time zones.  They said it couldn’t be done.  Or was that “shouldn’t”.  I need to listen closer.

 

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