Moonbows and a Quantum Fogbow

Last night I stumbled across a name I have been looking for since a sailing trip a couple of months ago, when I took this photo. I now know that the unusual phenomenon in this picture is called a 'fogbow'. It is similar to a rainbow in many ways, but the fog droplets are so small that instead of light being refracted it is instead diffracted, which leads to a white arc instead of the more familiar colours. Coloured and white bows can occasionally be seen at night, if there are the right atmospheric conditions and a bright moon, but these are given the fair name of 'moonbows'.

Apparently it also has something to do with quantum wavelengths, but that sounds like one for a rainier day than today and it's pretty wet out there as it is.

The Glamour... The Romance... The Mud...

There are those that suspect the Natural Navigator's life to consist of lying on the teak deck of a yacht musing about celestial bodies. It has happened, I cannot deny, and I do not wish to dampen such fanciful ideas, but it is not the bread and butter of this business.

There is a scene from that great movie, Point Break, where Johnny Utah (Keanu Reeves) is being shown round his new workplace, the armed robbery division of the LA FBI. His new boss is keen to dispel any romantic notions his green recruit may have of playing cops and robbers,

"Do you know how we nail the bad guys, Utah? … By crunching data. Good crime scene work, good lab work, and most importantly, good data-based analysis."

Johnny Utah goes on to disprove this mundane prognosis in solid Reeves style, but that is not the point. At least not the one I am trying to make.

The picture above is our data and it tells us a lot. This is a track with a lot of East-West in it as the sun has been shaded by the undergrowth more from one side than the other. The soft mud on the southern side has not been dried by the sun and has been eroded more by passing vehicles, it has reached the point where the original track has become near impassable and a vehicle has opted to divert around the larger puddle, creating a new track slightly to the south of the original. This may be the way the robbers headed...

Death and Life

I was reading about the death of a hiker on a walking forum recently and ended up posting a reply, it turned out to be a bit more of a sprawl than I expected. Readers of this blog should not be spared such ordeals, so here it is:

My work means that I have to try to understand the line between unreasonable risk and interesting challenge well. I also find myself drawn into the debate against my will occasionally if I get accused of recklessness.

There is not a lot of evidence that I am aware of that suggests that government involvement stops people from finding danger. There is however a strong theory that people will select the level of risk they are comfortable with, regardless of what others do. This is often illustrated by road safety arguments, the more 'safe' the roads are made the more dangerously the average person drives. There have even been calls from some quarters for removing all signs and road markings.

In the area of walking I think the are some parallels. I remember as a backpacker the number of signs warning against attempting the hike to the bottom of the Grand Canyon 'without x gallons per person of water, good levels of fitness etc'. Six hours later I sadly witnessed a grossly obese man die from a heart attack in the midday heat, despite there being a doctor on the scene.

I avoid prescription for others unless I am directly responsible for them, and on a personal level tend to take an 'overprepare and then take it on' approach. An amusing example of this was walking from Glasgow to London about ten years ago with a good friend. I had a good pair of trekking boots in my rucksack, but set off in a pair of £19 trainers to get clear of the city. I walked up the elevated section of the M4 into west London five weeks later without having put on the boots. Fell and Dale fell along the way without problem.

My work consists of undertaking regular natural navigation exercises: finding my way without using map, compass, gps or any other navigational tool at all. As you can imagine this gets those with an H&S philosophy of life into a bit of a lather. I am always clear to those I instruct and others that my pack contains: maps, compasses, GPS, mobile phone and, in the case of challenging environments, sometimes satellite phone and EPIRB too. I agree with earlier sentiments that an ability to call for help is not a licence to get into trouble, but waiting for things to really unravel is not the best option when an early 'PAN-PAN' call could improve the odds for all. I've not had to call on rescue services to date, but a respect for the fact that things can and do go wrong does help with the thoroughness of preparation considerably.

I attended a lecture at the RGS recently about a Greenland expedition in the '30s. A member of the audience asked at the end whether Gino Watkins and Co had a death-wish. Jeremy Scott gave an impressive reply, he said that he did not think that they believed death to be the worst outcome, he went on, 'if you find yourself watching daytime TV tomorrow you will know that there are worse things than death.'

The Near New Moon and Sunrise

Dawn is a critical and exciting time for the natural navigator, it sets up the day. It is also a time of rapid change, I took the second of these two photographs only one hour after the first yesterday morning, but that need not catch us off guard.

With experience it is possible to tell that this moon is two days off a new moon, which means that it will rise two of my fist-widths (24 degrees) ahead of the sun. The sun travels through the sky at just over a full fist width (15 degrees) an hour. It was therefore possible for me to gauge that the sun would rise in about one and half hours just by looking at the low moon in a dark sky.

Saturnalia, Christmas and Common Sense

A great morning for stargazing and one planet in particular was holding court. Saturn hung brightly in the southern sky between Virgo and Leo.

In astronomical terms Saturn is an impressive planet, the second largest in the solar system and girded by its famous rings. It also comes with as much religion and mythology as you could ask for on a crisp November morning.

Saturn featured very strongly in Roman religion as the harvest god, responsible for sowing, seed and most things agriculture. His festival, Saturnalia, was a time of much merriment and became the most celebrated of Roman festivals as tools were downed, slaves granted temporary freedom and 'certain moral restrictions were eased', and for all their seriousness in battle the Romans sure knew how to ease a moral restriction when they chose to. It was such a success that we are still feeling its partying power to this day. Saturnalia was originally celebrated on December 17th, but became a week long celebration and paved the way for our festivities at Christmas and New Year.

When Saturn was not busy doing all this he also lent his name to a day of the week, 'Saturday', from 'Saturni dies' in Latin.

While thinking this over I noticed something else less mythical and more tangible, the back of my head and ears were freezing. If a wind feels a lot colder than normal it often has some north in it, which like so much of understanding nature is common sense. A bigger slice of common sense was for me to stop shivering in my pyjamas and coat and get inside.

The Sun's Shadow in Winter and Summer

The last course stirred up some healthy discussion about the difference between the sun's summer and winter arcs in the sky. The arcs are actually very similar, because they are parallel, but in our winter the arc is displaced to the south. However, the effect this has on shadows is more interesting and beguiling. The arc traced by shadows over the year are not parallel, but change quite significantly from summer to winter. This is because the sun rises north of us in summer and south of us in winter. The effect this has on shadows is quite counter-intuitive, but no less fascinating for it. The chalk line in this photo shows how the shadow from the edge of a flower tub moved this morning. In the summer it would have curved the other way and closer to the pot.

RGS Past and Present

I had an enjoyable and full day yesterday holding a Beginner's Guide to Natural Navigation course at the Royal Geographical Society in Kensington. We were in the Lowther room for the day, one of the many rooms at the RGS that oozes character and a sense of history. Even when stepping into the room for the first time, a lot of people experience a feeling of familiarity as it has appeared in many films.

There was a great group for the course from very diverse backgrounds, from the art world to the military. Some of us were busy chatting over a cup of tea, about the room and the sort of figures from history that would have shared the same space, Shackleton and Co, when Sir Ranulph Fiennes passed us in the corridor.

It was one of those serendipitous moments that does no harm to the romantic mystique of the place.

One person's Mist...

When sorting some photos last night this picture - taken a few weeks ago on a very cold morning in Chichester harbour - came close to being deleted. I had a change of heart and decided to rescue it and elevate it to my blog. Rarely have the fortunes of a picture changed so suddenly or dramatically... OK, that's a bit much, not least since it is a rubbish picture. It's one redeeming feature and indeed its only feature is that the flash does help illustrate that fog is made up of lots of tiny droplets.

It is only a small step from thinking about such things to wracking one's mind desperately trying to understand the difference between fog and mist. They are essentially the same, it is a question of degree. Fog is just mist that you can't see very far in. Pilots define this being less than 1000 metres, but for others visibility has to fall below 200 metres for it to be classified as fog. This gives us the nice philosophical poser: if a motorist steps out of their car and into an aircraft the weather stays the same, but changes from mist to fog.

I really must get out more... or less.

Daylight Robin

A robin's trademark red breast has always struck me as one of nature's less enthusiastic attempts at camouflage. We went for a family walk in the woods yesterday and this particular robin was very friendly. Even so, when I tried to take a picture of him I sometimes lost him from view as he blended with the leaves.

Blue water sailors are aware that birds can be used in finding land, but walkers tend to overlook one of the simplest of navigational clues. The more friendly the birds, the closer you are to civilization. It's not just birds either, town foxes are becoming positively insolent.

The Many Faces of Chichester Cross

Chichester Cross is a slightly mysterious stone construction at the heart of my home town. It has been around for five hundred years or more and has endured its share of sun, wind and rain in that time. The two larger pictures show the effect of just 6 years of exposure.

The elements do not come at it from uniform or random directions though and so it feels the effects in different ways on each side. This leads to different erosion patterns and weathering marks. It also means that lichens find different sides more or less appealing. The smaller pictures show the edges of the eight flying buttresses. No two are the same.

Sailing on a Friday

This weekend I came afresh across the notion that setting sail on a Friday is bad luck. I had heard this before of course, but must have locked it out of my conscience because when I checked my logbook this morning I noted that the most substantial voyage I have ever undertaken, my singlehanded transatlantic, set sail on Friday the 7th of December 2007. I am extremely glad that I didn't think of this while I was still at sea on that crossing. It would have made me even more uncomfortable than the time I nearly went overboard whilst trying to save my St Christopher's medal and chain.

If you're interested in the Friday sailing superstition then there is an excellent entry in the Practical Encyclopedia of Boating by John Vigor.

GPS (Global Piglet System)

The worlds of technology, navigation and nature convened in a mildly surreal way over the past month.

Satellite navigation development, like all things space-related, often appears to be governed more by national pride than calm pragmatism. Nobody has yet explained effectively to me the need for billions to be invested in Galileo, the European alternative to the American GPS system. The Russian version of GPS, GLONASS, has not been a story of relentless success or necessity either, but apparently the system has now been tested on Vladimir Putin's dog.

'Mr Ivanov said that the equipment goes on a standby mode when "the dog doesn't move, if it, say, lies down in a puddle."

Mr Putin interrupted him jokingly: "My dog isn't a piglet, it doesn't lie in puddles.'

Squid Lights and Starry Nights

I gave a lecture at the Clothworker's Hall in the City last night. I think it went well, no rotten fruit or vegetables came my way at least. It did mean a night in a hotel and the need to fill some time in the usual Alan Partridge style. It was at the hotel that I read the cover story in this month's National Geographic about light pollution. All stargazers are aware of the problem and I thought that this was a story that had been done pretty thoroughly, but the NG approach was fresh and made for a satisfying read.

One sentence caused me to pause and then reread. After a second reading my jaw my have dropped a touch:

'In the south Atlantic the glow from a single fishing fleet—squid fishermen luring their prey with metal halide lamps—can be seen from space, burning brighter, in fact, than Buenos Aires or Rio de Janeiro.'

Leonardo's Tree Compass

Leonardo da Vinci is among the great and the good to have noted that tree growth is not symmetrical, it is heavily influenced by the wind and the sun. One of the consequences is a growth bias towards the south (in the northern hemisphere). This can normally be spotted more easily in the branches of a living tree, but a tree that has been cut down can also yield its secrets through its rings.

As the tree funnels its sap and energy towards the sun its trunk bends and distorts. This leads to thicker growth on the opposite, northern side and means that the heart of the tree is more likely to be found closer to the southern edge of the bark.

The theory is sound and it does work, but it can take a bit of practice to use well. The four pictures above are of cross-sections of the same tree, a beech that I found recently felled in nearby woods. It certainly has the potential to confuse and mislead. Nature is too interesting to be kind all of the time.

An Oily Afterthought

My posting this morning started me thinking about sun tan lotions. They have such great names: Hawaiian Tropic, Ambre Solaire, Bronze Ambition, even Piz Buin. These could be the names of Bond girls. Could this be because our love of the sun is so closely related to our need for escapism and fantasy?

Hawaiian Tropic Moss

There are three words that you are unlikely to see together in the same sentence ever again. What is my excuse here? There is a well-known relationship between sunshine and moss or lichen growth, but there are subtler, more interesting ones as well. I have lost count of the number of people who have confidently told me that moss only grows on the north side of trees and buildings. I have dealt with that partial myth elsewhere, but here I want to explore a rarely-noted trend.

In England and large parts of northern Europe mosses and lichens will often grow on the south side of trees and buildings, but they will nearly always display differences to nearby brethren growing on the north side. The crucial thing to remember is that we are dealing with trends and patterns when observing nature, avoiding rules wherever possible. The navigator who tries to live by the rule that moss only grows on the north side is likely to find themselves lost and bedding down on the stuff before too long.

The two pictures above show roofs on either side of East Street, Chichester. There is lush green moss growing on the north-facing roof, but if you look closely at the second photo you will see a brownish ochre growth running along the top of the south-facing, very sunny, roof tiles. This colour difference is a pattern that is quite consistent and satisfying to spot. The way I like to remember it is the 'Hawaiian Tropic Moss Trick', if you find what looks like normal moss that has has gone south with a bagful of lotion and lain on a bed in the sun for too long then the chances are it is south-facing. Beware though, this works well on buildings, but on trees the colour patterns change again. It will be their turn next week...