# Which Place Gets The Most Daylight?

So this puzzle isn’t about sunshine (the amount of time the sun shines from a clear sky), or even about the intensity of sunlight (which decreases with increasing latitude), but about cumulative daylight—the length of time between sunrise and sunset in a given place, added up over the course of a year.*

It’s a surprisingly complicated little problem. I addressed it using an antique solar calculator I wrote many years ago, using Peter Duffett-Smith’s excellent books as my primary references:

It runs in Visual Basic 6, which means I had to open up my VirtualBox virtual XP machine to get it running again. The original program calculates the position of the sun by date and time for any given set of coordinates, and also works out the times of sunrise and sunset.

You’ll see it gives sunrise and sunset times to one-second precision, which is entirely spurious—the refractive state of the atmosphere is so variable that there’s no real point in quoting these times to anything beyond the nearest minute. I just couldn’t bring myself to hide the extra column of figures.

Anyway, it was a fairly quick job to write a little routine that cycled this calculator through a full year of daylight, adding up the total and spitting out the results so that I could begin exploring the problem.

At first glance, it seems like there shouldn’t be any particular place that wins out. As the Earth moves around the sun, its north pole is alternately tilted towards the sun and away from it, at an angle of about 23.5º. If we look at a diagram of these two solstice points (which occur in June and December every year), there’s an obvious symmetry between the illuminated and unilluminated parts of the globe:

Between the solstices, the latitude at which the sun is overhead varies continuously from 23.5ºN (in June) to 23.5ºS (in December), and then back again:

So for every long summer day, there should be an equal and opposite long winter night. The short and long days should average out, during the course of a year, to half a day’s daylight per day—equivalent to 4280 hours in a 365-day calendar year.

And that would be true if the Earth’s orbit around the sun was precisely circular—but it isn’t. As I described in my first post about the word perihelion, the Earth is at its closest to the sun in January, and its farthest in July. Since it moves along its orbit more quickly when it’s closer to the sun, it passes through the December solstice faster than through the June solstice. This has the effect of shortening the southern summer and the northern winter. The effect isn’t immediately obvious in my diagram of solar latitudes, above, but it’s there—the sun spends just 179 days in the southern sky, but 186 days north of the equator.

This means that the total number of hours of daylight is biased towards the northern hemisphere. In the diagram below, I plot the hypothetical flat distribution of daylight hours associated with a circular orbit in purple, and compare it to the effect of Earth’s real elliptical orbit in green:

So far, I’ve been treating the sun as if it were a point source of light, rising and setting in an instant of time. But the real sun has a visible disc, about half a degree across in the sky. This means that when the centre of the sun drops below the horizon, it’s only halfway through setting. Sunrise starts when the upper edge of the sun first appears; sunset finishes when the the upper edge of the sun disappears. So the extent of the solar disc slightly prolongs daylight hours, and slightly shortens the night.

At the equator the sun rises and sets vertically, and the upper half of the solar disc takes about a minute to appear or disappear. An extra minute of daylight in the morning, an extra minute of daylight in the evening—that’s more than twelve hours extra daylight during the course of a year, just because the sun is a disc and not a point.

And if we move north or south of the equator, the sun rises and sets at an angle relative to the horizon, and so takes longer to appear and disappear—adding more hours to the total daylight experienced at higher latitudes. There’s a limit to this effect, however. When we get to the polar circles, we run into the paired phenomena of the midnight sun and the polar night. There are days in summer when the sun never sets, and days in winter when the sun never rises.  The extent of the solar disc can make no difference to the length of daylight if the sun is permanently above the horizon, and it can add only a few hours to the total as the sun skims below the horizon at the start and end of polar night.  And as we move towards the poles, the midnight sun and polar night start to dominate the calendar, with only short periods around the equinoxes that have a normal day/night cycle. So although the sunrises and sunsets within the polar circles are notably prolonged, there are fewer of them.

So the prolongation of daylight caused by the rising and setting of the solar disc increases steadily with latitude until it peaks at the polar circles (around 66.5ºN and 66.5ºS), after which it declines again. Here’s a diagram of daylight hours predicted for a point-like sun (my previous green curve) with the effect of the solar disc added in red:

And there’s another effect to factor in at this point—atmospheric refraction. As I described in my post discussing the shape of the low sun, light from the rising and setting sun follows a slightly curved path through the atmosphere, lifting the image of the sun by a little over half a degree above its real position. This means that when we see the sun on the horizon, its real position is actually below the horizon. This effect hastens the sunrise and delays the sunset, and it does so in a way that is identical to simply making the solar disc wider—instead of just an extra couple of minutes’ daylight at the equator, more than six minutes are added when refraction is factored in, with proportional increases at other latitudes. So here’s a graph showing the original green curve of a point-like sun, the red curve showing the effect of the solar disc, and a blue curve added to show the effect of refraction, too:

The longest cumulative daylight is at the Arctic Circle, with latitude 66.7ºN experiencing 4649 hours of daylight in the year 2017. The shortest period is at the south pole, with just 4388 hours. That’s almost eleven days of a difference!

So is the answer to my original question just “the Arctic Circle”? Well, no. I have one more influence on the duration of daylight to deploy, and this time it’s a local one—altitude. The higher you go, the lower the horizon gets, making the sun rise earlier and set later. This only works if you have a clear view of a sea-level (or approximately sea-level) horizon—from an aircraft or the top of a mountain. Being on a high plateau doesn’t work, because your horizon is determined by the local terrain, rather than the distant curvature of the Earth. So although the south pole has an altitude of 2700m, it’s sitting in the middle of the vast polar plateau, and I think there will be a minimal effect from altitude on the duration of its daylight.

So we need to look for high mountains close to the Arctic Circle. A glance at the map suggests four mountainous regions that need to be investigated—the Cherskiy Range, in eastern Siberia; the Scandinavian Mountains; Greenland; and the region in Alaska where the Arctic Circle threads between the Brooks Range to the north and the Alaska Range to the south.

The highest point in the Cherskiy Range is Gora Pobeda (“Victory Peak”). At 65º11′N and 3003m, its summit gets 5002 hours of daylight—almost an hour a day of extra sunlight, on average.

But Pobeda is nudged out of pole position in the Cherskiy Range by an unnamed 2547m summit on the Chemalginskiy ridge, which lies almost exactly on the Arctic Circle, giving it a calculated 5006 hours of daylight.

There’s nothing over 2000m near the Arctic Circle in the Scandinavian Mountains, so we can skip past them to 3383m Mount Forel, in Greenland, at 66º56′N, which beats the Siberian mountains with 5052 hours of daylight.

Finally, the Arctic Circle passes north of Canada’s Mackenzie Mountains, and between the Brooks and Alaska Ranges. Mount Isto, the highest point in the Brooks Range, is 2736m high at 69º12′N, and comes in just behind Pobeda, with 4993 hours of daylight. Mount Igikpak, lower but nearer the Circle (2523m, 67º25′N), pushes past all the Siberian summits to hit 5010 hours. And in the Alaska Range is Denali, the highest mountain in North America. It is 6190m high, and sits at 63º04′N. It could have been a serious contender if it had been just a little farther north—but as it is it merely equals Igikpak, and falls short of Forel’s total.

So the answer to my question appears to be that the summit of Mount Forel, Greenland, sees the most daylight of any place on the planet. I confess I didn’t see that one coming when I started thinking about this.

* “A year” is a slightly slippery concept in this setting. The sun doesn’t return to exactly the same position in the sky at the end of each calendar year, and leap years obviously contain an extra day’s daylight compared to ordinary years. Ideally I should have added up my hours of daylight over a few millennia—but I’m really just interested in the proportions, and they’re not strongly influenced by the choice of calendar year. So for simplicity I ran my program to generate data for 2017 only.

What I wrote at the start of this piece, about spurious precision in rising and setting times, goes doubly for the calculations concerning altitude. These results are exquisitely sensitive to the effects of variable refraction, and my post about the shape of the low sun gives a lot more detail about how the polar regions are home to some surprising mirages that prolong sunrises and sunsets. I can’t hope to account for local miraging, or even to correctly reproduce the temperature gradient in the atmosphere from day to day. I think the best that can really be said is that some of the contenders I list will experience more daylight than anywhere else on the planet, most years, and that Mount Forel will be in with a good shot of taking the record for any given year.

# Running Windows XP Under VirtualBox

As I write, it’s only another month until Microsoft’s free upgrade offer on Windows 10 expires (on 29 July 2016). I am so looking forward to that day, in the hope that it’ll mean an end to Microsoft’s intrusive little pop-up messages in the lower right corner of my monitor, and their increasingly devious attempts to trick me into accidentally upgrading. The experience is a little like having a weeping software engineer repeatedly grip your lapels, shake you gently, and sob: “But it’s cool. It’s free. Why don’t you want it? For pity’s sake, why? Why?

I don’t want it because it offers nothing I need or am even curious to see, while promising inconvenience and hassle during the upgrade process. When Microsoft are willing to pay me for the time I’ll spend on their “free” upgrade, then maybe we can talk.

But at present, I’m much cheered to be running Windows XP again, which marked the last occasion I ever felt a new Microsoft operating system actually constituted an “upgrade”. The fact that you can run a virtual XP machine in a window under Windows 7 or later is not as well known as it should be, and it has let me continue using some old software from that era that has resisted running in “compatibility mode” under later operating systems.

Text revised January 2021: Microsoft used to offer a Windows XP Mode for Windows 7 downloadable from the Microsoft Download Center, containing a virtual hard drive with an XP installation, but it has since been removed. However, the “Windows XP Mode” file WindowsXPMode_en-us.exe is still available from various download sites, such as CNET. But please be aware of the potential for downloading malware from the sort of sites that offer copies of discontinued files.

To get XP running under later versions of Windows, all you have to do is pull the virtual hard drive out of the WindowsXPMode_en-us.exe file. Since I wanted to run XP under a version of Windows later than Windows 7, I didn’t run the executable—I tucked it away in my Downloads folder. Embedded inside two layers of compression is the virtual hard drive I needed.

I used 7-Zip to find and extract the necessary file. 7-Zip is a handy, open-source archive manipulation program, which adds a couple of options to the Windows menu you see when you right-click on a file. So I navigated to where I’d stored WindowsXPMode_en-us.exe, right clicked on the file, selected “7-Zip” and then “Open archive”. 7-Zip then gave me a view of the contents of the archive file, which includes a folder named sources. In that folder, there’s a file called xpm. This is also compressed, so I right-clicked it and opened it in 7-Zip. In the archive listing for xpm, there’s a file called VirtualXPVHD. That’s the virtual hard drive containing the XP installation. I right-clicked it, and then selected “Copy to …”, telling 7-Zip to extract and decompress VirtualXPHD. I put it in a new folder called XP.

So that Windows could recognize VirtualXPVHD as a virtual hard drive, I now edited the file-name by adding a .vhd extension to it.

For an environment in which to run my new VHD, I downloaded VirtualBox, and installed it with the default options. Then I ran the program, told it I wanted to set up a new virtual XP machine using an existing virtual hard disk, and pointed it to the location of my VirtualXPVHD.vhd file.

And that was that. Now you I could launch an XP machine in a window on my Windows 8.1 desktop.

VirtualBox does a lot of handy things. There are a couple worth knowing about if you’re setting up your own virtual machine:
1) You can scale the window in which the XP machine runs, using the menu option View/Scale Factor. This is useful if you find yourself peering at a tiny window in the middle of your high resolution monitor.
2) At first, you’re going to need to let the XP window “capture” your mouse pointer. When you click inside the window, a dialogue box appears offering to capture the pointer. When you accept, you find your mouse is trapped inside the XP window. You can release it again by tapping a “hot key”, which defaults to the right control key on your keyboard. It’s worth checking that you actually have a right control key before you fire up XP for the first time, otherwise your mouse will be permanently trapped. If you don’t have one, you can change to a new hot key in the VirtualBox menu, File/Preferences/Input/Virtual Machine/Host Key Combination. Select the “Shortcut” box and press whichever key you want to designate as the new hot key.

I found the virtual machine was a bit crashy when XP was going through its initial set-up on my laptop (but not on my desktop). A couple of times I had to press the hot key to free up my mouse, and send a “power off” signal to the virtual machine using the VirtualBox interface. On each occasion it rebooted happily and let me proceed further with the set-up.

The first priority once you have the XP desktop on display is to add some additional function. Free up your mouse pointer so that you can use the VirtualBox menu at the top of the window, click on “Devices”, and then “Insert Guest Additions CD Image …” This makes the XP virtual machine think you’ve inserted a software CD, and it opens a set-up dialogue to let you install the new software. Accept this (and choose “Install Anyway” each time XP objects to the certification of the software that’s being installed).

Now you don’t need to go through the business of capturing and releasing the mouse pointer! The XP window is integrated into your desktop and behaves like any other windowed software. (On occasion, you may find that the mouse pointer behaves a little oddly in some programs—flickering, or scanning too quickly. On those occasions, capturing the mouse is useful. You can turn mouse capture on and off using Input/Mouse Integration in the VirtualBox menu at the top of the window.) I also found that installing the Guest Additions CD eliminated the crashes I’d been having during setup.

One hitch in all this was that XP soon announced that it needed activation, and demanded a Product Key. Now, back in the day, computers used to come with a copy of their operating system on a disc, and I still had the old XP installation disc for a long-defunct computer tucked away in a cupboard. I offered the Product Key from that disc, and XP was happy. In fact, I now have three virtual XP machines all happily registered with the same Product Key. Which is not unreasonable, given that Microsoft haven’t actually been supporting this operating system for a couple of years now.

A couple of the programs I installed under XP are so old they’ll only run if the parent disc is in a drive for them to access. That’s not exactly convenient, so I copied the necessary discs to .iso image files using DVD to ISO , and put the .iso files into a directory on my virtual XP machine.

Then I installed the Virtual CD-ROM Control Panel from Microsoft, which lets XP mount .iso files as if they were physical discs. (Note added, 2020: Sadly, this is no longer available to download from Microsoft. You can still find it on various external sites, but I can’t vouch for the cleanliness of the downloaded files, so I’m not posting any links here.) It’s slightly finicky to install, but the readme file talks you through the process. You need to move the .sys driver file to your Windows XP drivers directory, and then run VCdControlTool.exe to install the driver. Once the driver is installed, running VCdControlTool again lets you create an unused drive letter and then mount an .iso file to that drive. I set my .iso files up as “persistent mounts”, so they’re always available.

Finally, although I’m no great fan of cloud storage (sure, I’ll let a multinational corporation store my personal documents and photographs at some random location on the internet; what could possibly go wrong with that idea?) I do like to share a few program and configuration files between my various devices. The small storage capacity offered by the free version of DropBox has been more than enough for this—and anyone who cares to hack into my DropBox account isn’t going to find much that’s comprehensible to them, let alone useful. But DropBox discontinued support for XP recently, so I needed a way to transfer files from my XP virtual machine to a directory on its parent machine, where DropBox could then take over.

VirtualBox lets you set up folders that are shared between the XP virtual machine and the parent machine (go through Devices/Shared Folders) but some of my XP software is so ancient it refused to recognize the network drive on which these shared folders resided. So I tried using the free version of Tonido. Tonido synchronizes files through their server without ever storing them—I installed the server software on the parent machine, and the client software on the virtual XP machine. Presto! My shared XP files were transferred to the parent machine, where they could be DropBoxed or backed up as required. This had the advantage of being easy to set up, but the rather bizarre and deeply unsatisfying consequence of a computer transferring files to itself over the internet. It also has to be said that the Tonido file synchronization was often slow, and on occasion delayed for hours.

Anyway, once I’d got that straightened out, I used the Devices menu in VirtualBox to make the DropBox folder on the parent machine a shared folder, ticking the boxes to make it “auto-mount” and “permanent”. It then appeared as a network drive the next time I booted the virtual XP machine. Using Link Shell Extension in XP, I could pick folders inside the DropBox network drive, and drop copies of them as symbolic links on the XP c:\ drive, where my ancient programs could see them. When the programs modify those files, the modification is then reflected in the DropBox folder on the parent machine, and that cascades off to my other devices, and their virtual XP machines. Joy!

So now, every time Microsoft offers me a free upgrade, I can sit back and enjoy my free downgrade instead.

# Pennycook et al.: On the reception and detection of pseudo-profound bullshit

This from the November 2015 issue of Judgment And Decision Making. Here are links to the original paper (pdf) and its supplementary tables (pdf).

The authors seek to find a preliminary answer to the questions, “Are people able to detect blatant bullshit? Who is most likely to fall prey to bullshit and why?” Their study is therefore of the characteristics of the  bullshittee, rather than the bullshitter, or of bullshit itself.

They suggest that bullshit occupies a sort of halfway house between lie and truth. Bullshit is “something that is designed to impress but […] constructed absent direct concern for the truth.” (That is, the author of bullshit doesn’t care whether it’s true or not, in contrast to the liar, who is deliberately subverting the truth.) And “bullshit, in contrast to mere nonsense, is something that implies but does not contain adequate meaning or truth.”

I’m indebted to them for providing links to two sources of pseudo-profound bullshit, used in their study.

One, Wisdom of Chopra, uses random words taken from the Twitter feed of Deepak Chopra to construct novel sentences. Here’s an example of its output:

The unexplainable arises and subsides in the doorway to energy

The other, Seb Pearce‘s New-Age Bullshit Generator, generates an entire, beautiful page of random bullshit. Here’s one headline:

You and I are entities of the quantum matrix. By evolving, we believe

So that’s all pseudo-profound bullshit.

According to Pennycook et al., reasons you might mistake that for actual profundity include:

• A deficiency of analytic thinking
• Ontological confusion (confusing different categories of existence, such as the mental and the physical)
• Epistemically suspect beliefs (such as paranormal or supernatural ideas)

Four studies are reported in the paper. They all look for correlations between the particular cognitive biases listed above with a “Bullshit Receptivity” scale—a measure of an individual’s tendency to rate randomly generated bullshit as “profound” on a five-point scale ranging from “not at all profound” to “very profound”.

I haven’t even counted the number of separate correlation measures to which the authors assign significance values; I’ll leave that as an exercise for the  Interested Reader.

But what we seem to see is that:

• Participants tended to score random nonsense as moderately profound.
• Participants scored selected real Deepak Chopra Tweets as a little more profound than random nonsense, but less profound than some motivational quotations.
• Some participants scored even mundane statements like “Most people enjoy some sort of music” as having some level of profundity. These participants tended to give high profundity scores across the board.
• To quote the authors: “Those more receptive to bullshit are less reflective, lower in cognitive ability (ie. verbal and fluid intelligence, numeracy), are more prone to ontological confusions and conspiratorial ideation, are more likely to hold religious and paranormal beliefs, and are more likely to endorse complementary and alternative medicine.”
• Waterloo University undergraduates (or at least, those who sign up for this sort of study) are catastrophically gullible, assigning various levels of profundity to some quite astonishing twaddle (Table 1). Snake-oil salesmen are presumably converging on the campus even as I type.

So it’s good to have all that sorted out.

# Book Collector

When you have more than 4000 books scattered around the house, it gets difficult to find the one you’re looking for. Especially if you’re hunting for a short story and you can’t quite remember which book you read it in. This used to happen a lot, chez Oikofuge. But not any more.

Book Collector is a book cataloguing program from Collectorz.com, and it’s the best I’ve run into. I can’t now imagine life without it.

Data entry is easy, and highly automated. If your book has an ISBN, you can type it in or scan it with a barcode reader, and the basic book data are pulled down off the Collectorz.com central database. These days, the ISBN is readily visible on the back cover, but with older books (1967 to the mid-70s) you may have to look for numbers written on the spine, or listed in the front matter. Some UK publications of that vintage have nine-digit SBNs instead of ten-digit ISBNs, but the conversion is easy—just add a zero at the left end.

Before 1967, there were no ISBNs, but Book Collector also lets you add books automatically by entering the author and title. This option will bring up all matching entries in the Collectorz.com database, so you might need to do a little poking around to find the entry that matches your specific edition.

That will get the basic data into your database, including a version of the cover art if it’s available. But the software offers a huge number of additional relevant data-fields, which you can fill in or ignore according to your wishes. (You’ll probably want to make use of the “book location” field, unless you have a memory much better than mine.) It even lets you create custom fields.

The on-line cover art comes from a variety of sources—it varies in size and quality, and can occasionally be for the wrong edition of your book. But Book Collector has an automated search facility that lets you look for more cover art on-line. It also lets you add your own art by scanning the cover. If you’re of an obsessive nature (who, me?) you may find yourself scanning a lot of book covers to get precisely the right edition.

You can view your database in various ways, usually splitting the view between some sort of overview of the books, and a detailed view of a specific volume. The overviews available are a “bookshelf” depiction of cover art (which I find useful when browsing for a specific book) and a spreadsheet-type display of multiple customizable columns. There’s also a “cover flow” option available, but the less said about that the better—it’s the sort of triumph of style over utility that could only appeal to an Apple user.

You can choose from a growing number of different formats for viewing your book details; or, with a little knowledge of HTML/ XML, and some digging around in the file structure, you can customize up your own view.

Searching is easy. There’s a quick-and-dirty search option that just looks for your chosen text anywhere in the book’s description. It’ll bring up false hits, but often it lets you narrow down the display enough to zero in visually on the book you want. But you can also create moderately sophisticated “filter” views, using simple Boolean logic functions, to pull out the books you want.

As someone who has a lot of short stories in my book collection, I particularly value the fact that I can enter a contents list for my books. Book Collector offers you a cut-down database and user-defined fields for each short story in a book. Unfortunately, the contents list won’t come down to you automatically from Collectorz.com—manual entry is required, which can be tedious if you have a lot of “complete works” volumes on your shelves. And I would appreciate it if Book Collector some day offered a detailed view by short story as well as by book. But that’s a minor niggle when I can choose to display anything I want in the columns of the spreadsheet view.

What else? Collectorz.com offers a cloud storage facility, so you can be sure you have the same data on all your devices. There’s a responsive Support team (I’ve only ever had to use them once) and an active users’ forum where people are happy to help out with minor queries. And there’s a free try-before-you-buy download.

If you’re in the market for book cataloguing software, do give it go.

# Software: Introduction

I started computer programming on punched tape and IBM 80-column punched cards, using Fortran, back in 1974.

One of my first teachers was a young woman who could read the program directly off the punched tape, and debug it using a hole punch and some sticky dots. I fixated on her utterly, like a baby duckling.

Later, I moved on to Teletype terminals, on which I programmed primitive astronomy calculations. Then my very own computer (who saw that coming?) the Sinclair ZX Spectrum, plugged into the television, on which I built a primitive model of the solar system using early editions of Peter Duffett-Smith’s fine astronomy programming books.

Apple IIs and PCs after that, mainly working in various dialects of Basic, and then making the switch to event-driven Visual Basic when it came along in the early 90s.

I produced and published various utility programs for the medical specialty I worked in, and even sold a couple of units of a reference-manager program I wrote as an add-on for the early scientific word processor, ChiWriter. But it was all essentially recreational until I made the mistake of writing a rostering program for the department I worked for in 1997 (out of frustration with the very poor quality of commercial rostering software at that time). That put me on a maintenance treadmill for the next fourteen years.

So I rather lost interest in developing any more complete software packages at that point! My other programming activity therefore became confined to writing little routines to get some particular piece of data-handling or calculation done, as part of some other project. I did a lot of that when I was a developer on the open-source 3D planetarium software, Celestia, and also when accessing NASA’s Shuttle Radar Topography Mission data to research mountains for Ginge Fullen’s Africa’s Highest Challenge, in which he climbed the highest point of every country in Africa.

I have a number of little software projects in mind for the future, some of which I may share here. But I think initially this category of blog post will be devoted to a couple of reports on software I find useful and/or fun, and want to recommend.