Thursday, January 31, 2019

Go Towards the Light | Direction and Time from the Sun

Finding North using primitive means is a frequently discussed outdoor skill. But what about deriving the current time? I hadn't seen this discussed until I came across a chapter in this book: Graves' Bushcraft: Time & Direction. Near the start of the chapter is this description of how the Sun moves:

As you know, the sun crosses the imaginary North-South line (Meridian) every day when it reaches its highest point (Zenith) above the horizon.

Therefore when the sun is at its highest point in the sky it is North or South of you, depending upon your position on the earth's surface, and the sun's position relative to the earth's equator.

For all practical purposes there are twenty-four hours between each sun crossing of your North-South line, or Meridian. During the twenty-four hours the earth will have revolved apparently 360 degrees; therefore it will move 15 degrees for each hour, or one degree in four minutes. This is very convenient to know, because if you know the North or South accurately, you can easily measure off the number of degrees the sun is from the North-South line, and this will give you the number of hours and minutes before, or after noon.

Whoa. I'd always appreciated that for most of the world the Sun doesn't rise due East and it doesn't set due West. But the above description started me thinking about what could be learned from the position of the Sun. After further research I've come to appreciate just how closely mapped our definition of time is to the position of the Sun. In short, with the right math, you can derive one from the other.

You might think, thanks to clocks, compasses and GPSs that such math had been relegated to the history books. But thanks to the popularity of solar power, the need to understand the relationship between the Sun, time and its location is more important than ever. This explains why the most useful resource I found on the topic was provided by a photovoltaics education site, The site not only includes textual and mathematical descriptions of each of the concept needed to understand solar motion, it also provides useful Adobe Flash Animations for the visual learners among us.

Using the formulas provided by my goal was to write sun-posn, a function that would take in latitude, longitude, timezone offset, day of year and hour of day and return elevation (how many degrees above the horizon the Sun appears) and azimuth (the compass location of the Sun) of the Sun. You can find my code here, and it's little more than a direct translation of the math on

Here's an example of my code in action; even provides a Sun Position Calculator to check my work.

(define dc-lat  39)
(define dc-lng  -77)
(define dc-tz  -5)

> (sun-posn dc-lat dc-lng dc-tz 30 14.75)
(23.801254841102036 . 217.5548315173389)

This is a clumsy way of saying that on the 30th day of the year (January 30th), at 14.75 hours into the day (2:45pm for us Americans), in Washington, DC (located roughly at 39° latitude, -77° longitude), the Sun will be 23.8° above the horizon, and at a compass heading of 217°. The Sun Position Calculator agrees:

The calculator reports that sunrise is at 7:23am on the 30th. We can verify this by running sun-posn for 7:23am:

> (sun-posn dc-lat dc-lng dc-tz 30 (ts->hh '(7 23)))
(0.08264850607002976 . 113.56028175854931)

Sure enough, the elevation of the Sun at 7:23am is essentially 0 degrees, or at the horizon. This also confirms that the Sun won't rise due East on that day (that is, 90°), but will rise a bit to the South-East, at 113°.

I can see at least two practical uses for the above code. First, I could imagine printing out a table of times, elevations and azimuths to take along on a backpacking trip. For example, suppose we were going to spend a week tramping through Yellowstone this summer. The following cheat sheet would be useful to take along:

(let ((ys-lat 44.560184)
      (ys-lng -110.574387)
      (ys-tz -7)
      (doy 196)) ; July 15th
  (for-each (lambda (hour)
              (show hour ': (sun-posn ys-lat ys-lng ys-tz doy hour)))
            (range 6 22)))

(6 : (-8.122303097656218 . 48.6594818098441))
(7 : (0.5365311423839506 . 59.630576190043215))
(8 : (10.190122452394226 . 69.75648575008768))
(9 : (20.484132757573843 . 79.53460931955374))
(10 : (31.109204936949766 . 89.60026010481032))
(11 : (41.737732404109586 . 100.87684292551032))
(12 : (51.90078297793876 . 114.94012790883353))
(13 : (60.700607362562444 . 134.66593632819524))
(14 : (66.2502736763883 . 163.72111937212864))
(15 : (66.02370239562663 . 198.65009244190927))
(16 : (60.156074073818786 . 226.9987719193552))
(17 : (51.213200952664465 . 246.19564570960074))
(18 : (40.995394625941636 . 259.98702370894995))
(19 : (30.35442787972579 . 271.1370821667874))
(20 : (19.74268533460884 . 281.1568990798108))
(21 : (9.483505182779895 . 290.9408405387917))
(22 : (-0.11225447575466428 . 301.1113559320821))

Whoa - in theory, we'd have daylight from just after 7am until nearly 10pm. With this data in hand, a quick glance at a watch and the Sun would tell you direction. Alternatively, you could use your compass and the Sun to derive the current time. This information on a laminated card would be a weightless, indestructible, battery-free navigation and time telling tool. That's hard to argue with, no? Technically, the elevations and azimuths would vary day to day, but for all practical purposes, a chart showing a single day of the week should be effective.

A second use for this data: to help you buy tickets at an outdoor sporting event. After having baked in the sun at a number of outdoor tennis matches, I can see how invaluable it would be to understand the path of Sun throughout the day. In winter, sunshine may be a precious resource worth coveting. Either way, adding the Sun's position throughout the day to the list of variables you factor into buying tickets is an obvious win.

Next up I plan to repackage the above functionality into an easier to use facility. Stay tuned.

Wednesday, January 30, 2019

A Landscape Translated into Liquid Glass

I mentioned we picked up a vase in New Zealand. Here's a few pics of it:

The pictures really don't do it justice. It's part of the Volcanic Series, produced by Lava Glass New Zealand, and is described thusly:

In the Volcanic Series master glass artist Lynden Over explores New Zealand’s scenery. He uses a layering technique where trails of liquid glass are controlled to create coloured landscapes.

What I find so remarkable is how well the abstract design captures the perfectly blue and turbulent waters of Huka Falls, the inspiration for the piece. See what I mean?

What a powerful reminder that abstract art can capture a very non-abstract moment in a powerful and meaningful way.

Tuesday, January 29, 2019

New Zealand Adventure - Day 5

[Composed 1/10/2019]

Man vs. Nature: who moves water better? That's the question our hike answered today, which started at Huka Falls and ended at Aratiatia Rapids. The falls are an impressive natural phenomena, which show the power of nature to move 58,000 gallons of water per second over a cliff. Aratiatia, on the other hand, is a man made spectacle. Throughout the day, the Aratiatia dam is opened up, and a calm section of river turns temporarily into a raging set of rapids. While I certainly enjoyed watching Aratiatia do its thing, I think Nature wins this round and Huka Falls edges out the rapids as a more impressive site.

Between the two sets of rapids is a 4 mile section of trail which takes you through a forest, open grass lands and a palm forest. It was a great hike, though like all our experiences in New Zealand so far, as soon as that sun comes out it gets hot! I mean, really, really hot.

We saw unusual plants and bird life along the hike. What was also notable is what we didn't see: any mammals scurrying around. The critters we consider part of a healthy ecosystem (rats, squirrels, rabbits, chipmunks, weasels, etc.) are invasive predators and have been eliminated. We saw a number of signs and traps along the way that announced the area was pest free.

After our hike we checked out a number of the local stores in the area. This included a honey store where we sampled mead, honey liquor, honey schnapps and honey whiskey. The winner, by far, was the butterscotch honey schnapps. We also checked out Lava Glass, a glass studio in the area and took in a bit of glass blowing. This is a working glass studio, so we caught them working on manufacturing today's product: a lava "rock." The individual making the 'rock' would collect up some glass, dip it in shards of colored glass, shape it into a rock, add a bit of imperfection to the sides and then repeat. It wasn't the most exciting thing to watch someone create, but it was neat to see the process up close. We picked up a glass vase from here. Its light blue color and swirls of white represent Huka Falls, which we'd visited early in the day.

Dinner tonight was at an all vegetarian Indian restaurant. All the food was good, but the appetizer we got was off the charts delicious. Imagine a sweet and fried sesame chicken type dish, but replace the meat with french fries. Wow. I'm telling you, someone is going to bring this dish to the states and it's going to be huge. So tasty. I also had cheese stuffed naan bread, which while probably not particularly authentic, was still quite tasty.

Monday, January 28, 2019

We Escaped! Fun Times at the Runaway Train Escape Room

51 minutes, 14 seconds. That's how long it took for the 6 of us to bust out of the Runaway Train room at the Columbia Maryland, Breakout Escape Room. This is Shira and my second Escape Room, the first one being a Sherlock Holmes themed room in Alexandria, Virginia.

We had an awesome time (thanks cousins!) and feel like we're really getting the hang of this Escape Room activity. My two big take aways were:

1. Ask for hints. In our first escape room, we got the impression that we should be able to solve the room without any assistance. That was silly, as we had only a basic understanding of what we were trying to accomplish. For our second room, we had a much clearer idea as to how to solve problems, but were smart enough to ask for hints to keep the whole show moving. Our game master was top notch because regardless of the hint we asked for, she gave us just enough information to move forward.

2. There was a surprising consistency between our two escape rooms. While the two Escape Rooms we participated in were different genres and were hosted by different companies many of the same puzzles and tactics were employed. Not to mention, the level of difficulty was about the same: each challenge must be non-trivial, yet it does no good to over-think them. In short, the code for the lock isn't going to be 1-2-3-4, yet, it's not going to require you to use employ calculus.

Because the rooms are solved using similar strategy, I get the sense that it would be smart to do a few more rooms with hints and *then* attempt one without assistance. Ultimately, it's about building up a library of puzzle types you can refer back to, and sharpen your observation skills.

The kids did great in the room, and there were some challenges that they could absolutely participate in. Yet, there were some hurried moments when the adults were busy trying to decode something and the kids were left twiddling their thumbs--not fun. Still, it was great to share the experience with the kids and I'm glad they put up with the down time.

Escape Rooms are clearly a fad of the moment. But that doesn't make them a bad thing. Go, give one (or two, or three) a try. Just make sure you bring the right people along, like we did last night, and you, too will escape!

Sunday, January 27, 2019

New Zealand Adventure - Day 4

[Composed 1/10/2019]

Goodbye, Auckland, hello, open road! Can I just say how amazed I am that Shira can confidently drive on the left hand side of the road?

Our destination today is the town of Rotorua, with two planned stops along the way.

The first stop was at the Zealong Tea plantation. Think fine wine, but with tea as the beverage of choice. We got a history lesson and description of the process used to make the tea, and of course a tea tasting. If a time traveler from hundreds of years ago were dropped into Zealong, they would find the process of making tea eerily familiar. The fields of tea plants are still hand picked by individuals wearing the same large brimmed hats and oversized bandanas that were used back in the day. The oolong tea leaves are still put in bags and wound tightly to create the signature curled look, and the leaves are still oxidized on bamboo trays. The packaging is modern, but the process remains traditional.

We tasted a number of teas, from green to black. What was perhaps most surprising was that after drinking the oolong tea our hostess was able to unwind one of leaves and there were was an intact tea leaf, rehydrated. I guess I'm so used to cheap bags of tea I never stopped to imagine how high quality tea looks, smells and tastes. I'm not ready to give up on Trader Joe's Irish Breakfast tea, but I certainly enjoyed playing the tea snob if, only for a couple of hours.

After our tour and tasting we were served high tea; the first Shira and I have ever had. Wow, this is living! There was a variety of savory vegetarian friendly treats and then some incredibly delicious pastries. Yum!

A couple hours later we found ourselves at the entrance of a cave in Waitomo. Our guide took us 6+ stories down into the Earth, where we toured one of the area's caves. In many respects, the cave was much like Luray or Skyline Caverns. The path we walked along was packed with amazing stalactite and stalagmite formations. The big difference, as far as I can tell, is scale. My sense is that the cave we were in was quite a bit larger than Skyline or Luray. But of course, that may just be my memory playing tricks on me.

One unique aspect of the caves is the presence of glowworms. This is the second new form of bioluminescence we've see in as many months. The first was a bioluminescent bay in Puerto Rico which left us underwhelmed. The glowworms were definitely more impressive, as they were brighter and larger. Like the bioluminescence of Puerto Rico, what makes the glowworms remarkable is their life cycle. Glowworms aren't worms at all, but maggots, and each one has a fishing-line type device that it deploys to catch food. The adults apparently only live a couple of days, and because their only role is to mate and lay eggs, they don't have mouths to eat. The whole cycle is baffling and leaves you marveling at how diverse nature can be.

Bringing along a tripod wasn't an option in the cave, so I had to improvise to get any sort of pictures of the glowworms. My work around was to shoot 10 second exposures and just accept that there would be some camera movement. The photos below of the blue squiggly lines are the results of this. Instead of blue streaks, imagine fixed blue points, and that's what you can expect glowworms to look like in person.

One of the most impressive features of the cave was a limestone pillar placed near the entrance by the owners of the cave. It's positioned below a dripping stream of water. Looking at the pillar, it's not much to see: it's oddly shaped, but not nearly as elegant as the features nature created within the cave. What is special about the pillar is that 13 years ago it was a flat, evenly formed piece of stone. In just 13 years, the water has cut noticeably into the rock. I think of the geologic formations taking millennia to form, but dripping water made a noticeable impact in just over a decade.

The New Zealand countryside has made for a beautiful backdrop as we covered the distance between Auckland and Rotorua. The cave and tea plantation were wonderful examples of the magnificent natural wonders New Zealand has to offer. Fun times all around!