March 5, 2010
Lights in the Sky
Over recent days there have been a variety of transient atmospheric phenomena, fleeting lights in the daytime sky. They are mostly associated with thin high cloud, Cirrus, Cirrocumulus and Cirrostratus and their various species – yes, clouds have species! As these clouds are mostly composed of minute ice crystals when the sun shines through them, depending on the shape and angle of those crystals, they may act as tiny prisms refracting the light and splitting them into rainbow colours.
To see them, first you have to be aware that conditions are right for them to occur. Sunshine is a precondition, plus any amount of the aforementioned cloud to make it hazy. Then you have to look for them. Unlike ordinary rainbows which occur opposite the sun, most of these other effects occur in the direction of the sun. We rarely look that way, with good reason – it can permanently damage your eyes. So wear good sunglasses, position yourself with something between you to screen the sun, such as a tree, or shield it with a hand or a book.
The commonest phenomenon is the 22° halo. An outstretched hand at arm’s length should cover the sun with the thumb, while the tip of the little finger rests on the circumference of the ring. This won’t be enough to shield your eyes though. For most of this day’s observing I stood in the shadow of our chimney stack. The 22° halo sometimes has additions – extra rings or arcs associated with it, some of which are very rare, and for that reason plus its sheer beauty it is always worth photographing, in my opinion.
22° halo and sundog
Commonly associated with halos are sundogs – there is one faintly visible in the halo photo and a second taken at sunrise on the following day.
Apparently, these are formed by light refracting through crystals that are shaped differently from those that create halos. The two together tells of a mix of crystals in the high atmosphere and also extends the possibilities of what light shows may be seen. Sundogs sometimes have a white outer extension. The right hand sundog from the sunrise display began to stretch some distance and was very intense.
This was the beginning of a parhelic circle (par – through, helic from Greek helios – sun). Occasionally a white line may encircle the whole sky, passing through the sun. I have observed this only twice and it is quite a surprising sight, I can assure you!
Parhelic Circle March 27 2009 (has had unsharp mask applied to emphasise the ring)
Parhelic Circle June 14 2008 - this doesn't encircle the sun but passes through it!
The final crystal induced effect was a circumzenithal arc (circum – around, zenith – sun’s highest point in the sky). It happened when the sun was low and occurs quite a distance from the sun. It resembles an upside down rainbow with the centre of the bow sunwards and red on the lower surface. Although the colours can be intense it is difficult to photograph, in my experience.
Circumzenithal Arc - at the zenith, way above a low sun
The particular conditions that brought about these effects – a collision between cool and warm air masses – also created a different optical phenomenon – irisation or iridescent cloud. Newly condensing cloud, also at fairly high altitude, may be formed of super-cooled water droplets rather than ice crystals. These refract light differently and produce beautiful pastel hues close to the sun – sometimes too close for comfort. I was lucky with the position of the chimney stack and I mostly let my camera do the looking. Wearing sunglasses will allow you to observe this effect more often. The same thing occurred next morning but the light was too intense to photograph though I saw it clearly through my shades.
Iridescent cloud
growing iridescence
intense iridescence
What does all this mean to bushcrafters? Well, it is always good to improve your powers of observation and your awareness of Nature. On the day that most of these phenomena occurred, it was evident to me from watching, that the clouds aloft were moving in the opposite direction from the wind and clouds near ground level. The upper air was moving in from the SW and therefore likely to be warm and moist originally. The lower wind was a chilly ENE, a cold air mass undercutting the warm and forcing it upwards where it cooled, showing an incredible mix of lively Cirrus formations and very long aircraft condensation trails, indicating that it was unstable. Something similar can be created by the approach of a warm front, but in this case the nearest front was halted over Ireland so the weather did not deteriorate further. It was worth keeping an eye on all the same. The atmospheric phenomena I witnessed can portend a change and with the warming of the Northern Hemisphere as Spring approaches there will be further collisions between warm and cold air masses over the British Isles which will bring about further opportunities to observe lights in the sky.
Although halos and sundogs have been known of for thousands of years (Pliny the Elder wrote about them in his Natural History from the 1st Century) a number of explorers and observers of Nature, notably William Edward Parry in 1820, Tobias Lowitz in 1790 and Gerald E Owen in 1935 were the first to see and record the rarer arcs and related phenomena. Some managed to have arcs named after them. While today it is a subject of proper scientific study the amateur observer still has a role to play.
February 16, 2010
Stories in the Snow
With snowfall in this country there is often a limited window of opportunity to make the most of your tracking skills before a thaw sets in again. If you are tied to a daily job (I am lucky enough to be self-employed) you also need it to snow at the weekend! Still, it is worth persevering for a large amount of experience will come your way in a short space of time. There is more snow to come for many parts, so make the most of it.
Good snow, perfect tracking snow – settling all day to a depth of say 10cm and not freezing hard, nor melting at all at night when most creatures are active or all the next day while you are out in it – not only reveals exciting little details but also the big picture of what is about and where they go. The later in the season it falls, the more activity you are likely to encounter; the early winter lethargy of many animals will have passed and fat reserves run down, so food will take higher priority. Badgers, for instance, begin to move around more as pregnant females make space for themselves, perhaps evicting some other sows and younger boars from the sett in the process. Much seasonal activity is dictated by day length and that inexorably gets greater as we move towards spring.
The most recent snowfall (here in my part of Kent) spoke volumes. As I stepped out of my door I immediately learned that we have a Wood Mouse (or possibly the closely related Yellow-necked Mouse) or two, using our coal bunker as a thoroughfare. The curious cloven-hoof-like tracks of a mouse hopping in snow can be quite a puzzle if you have never encountered them before. In February 1855 large numbers appeared in the snows of rural Devon and were not generally understood for what they were. They caused such a stir that some folks thought they were the footprints of Satan himself and the incident was reported in The Times!
A close look, in most cases, will reveal the imprint of the tail. That said, a little while later, in the woods I found a hopping mouse trail with no tail drag. (see photos below) That trail also followed the mouse’s outward line on the return journey, making a confusion of prints that needed unpicking.
The direction of movement is indicated by the wider gap. This is made by the hindfeet landing ahead of the forefeet. A Rabbit (inset) shows something similar but greatly scaled up.
hopping mouse leaving no tail marks; what a strange beast it appears to have been
Bear in mind that two way trails are common with many mammals. A small creature like a mouse or rabbit will have a learned route that they can flee down in moments of danger without a thought or hesitation, so ingrained that they know where every obstacle is for an instant manoeuvre.(It has been shown by experiment that for a while they still jump over objects that have been removed.) Other animals follow scent trails that they have laid down, Badger and Fox, for instance, but the Fox also has excellent vision and may follow his own trail by sight.
Just to try to confuse you, a single line but the Fox both came and went this way
Here is an example of where a Fox has struck out over a rather wide open area but has stuck almost exactly to the trail it had left previously. You can see that in places the animal deviates from line slightly (probably to investigate a scent) but otherwise holds it tight. These tracks led to (and from) a spot where there had been a lot going on. I thought it may have been hunting activity but there was absolutely no sign of prey, just indications of more than one Fox. Then I realised it was play, probably between dog fox and vixen as the mating season is only just coming to an end. Aside from a patch where one animal had rolled in the snow, there was a beautiful example of a four-footed pounce, with a brush mark, something that a Fox usually does when catching mice or voles.
A typical vole-catching four-footed pounce but no sign of prey; just play
I didn’t get very far in four hours, there was so much to see. More woods and a river nearby but not the time on this occasion. Probably the most strangely beautiful sight of the day was the double imprint of a Blackbird that had inadvertently landed in deep snow and floundered, leaving the impressions of fanned wings and tail, feet and even chin and beak.
A real 3-D effect this way round (the white patch is a Fox footprint made later)
February 12, 2010
The Bushcraft Magazine meets Fergus the Forager
The Bushcraft Magazine meets Fergus Drennan whilst he is out foraging for seaweeds on the North Kent coast.
January 27, 2010
Mars Goes a Wandering
The night sky is a good place to test your powers of observation. Are you clear which ‘stars’ are actually planets? Do you, as our ancestors did, notice their wanderings around the constellations? Have you observed how they stay within a relatively narrow band of the stars – the ecliptic or Zodiac?
Well if haven’t, don’t feel too bad. There are wheels in motion within wheels and keeping track can be challenging to non-astronomers. In addition to the daily rotation of the Earth causing everything to slide out of view over a period of hours there is the Earth’s passage around the Sun, the Moon’s orbit of the Earth, the periodic disappearance of those planets behind the Sun, and the tilt of Earth’s axis to contend with, for example. If you were up all night every night under clear skies, you would soon pick up on some of the more local activity – that of two inner and three outer planets. Busy lives, cloudy skies and our own diurnal (opposite to nocturnal) nature make it very difficult.
Now is a good time to look up and catch an observable event. Mars, the red planet, is at opposition. Opposition is when the Earth and an outer planet line up on the same side of the sun. In the same way that the Moon is full when it is at opposition, the face of Mars visible from Earth is completely illuminated. It is also visible pretty well all night, rising around sunset, riding high at midnight and setting around sunrise. It is at its closest to the Earth since 2008, making it appear bigger and brighter than at any time from then until 2012!
Looking East January 26 2010 at 21:00 – 22:00 10 second exposure at f 5.6, ISO 400
It not only looks striking but something else is going on, too. During November 2009 Mars was slowly trekking through the constellation of Cancer. As it continued its journey East, it moved into the Constellation of Leo in December but early in January 2010 it appeared to turn around and head back towards Cancer, travelling Eastwards again. This is known as retrograde motion and is really an illusion caused by the fact that Earth (being nearer the Sun) moves in a faster orbit – Mars takes almost two Earth years to complete a round trip. For a time Earth overtakes Mars causing it to seem as if going backwards (we’ve all seen this effect whilst in cars and trains), but because the motion of both planets is a circle not a straight line, we swing back to our relative positions again, albeit much further apart. If that’s not clear, then watch this lovely little video on You Tube; not one of mine I’m sorry to say. Retrograde Motion and the Opposition of Mars
Mars is back in Cancer again. Cancer is a faint constellation and the bright moonlight bleaches it out at the moment. On January 29th the Moon, which moves much more quickly West to East than Mars, will be full in Cancer, also, probably expunging all the local stars. However Mars, very close by, will continue to shine brightly. As the moon wanes it will start to appear later and later in the night sky and not interfere with seeing Mars, which will remain prominent for a couple of weeks. (Leave that to the clouds). On March 11, 2010 the planet will turn around and start heading back towards Leo again. As it does so it will become progressively fainter, a far cry from the red eye presently burning a hole in the night sky.
One way to follow this is by taking photographs at intervals of a couple of days. You will need a tripod. For the image I took a 10 second exposure at f 5.6, ISO 400. Use the self timer or shutter release to avoid shaking the camera initially.
January 20, 2010
Velvet Shanks / Enokitake
Velvet Shanks (Flammulina velutipes) are a genuine Winter mushroom that don’t begin fruiting until December or even January. They grow on dead wood particularly the stumps of Elm, where they can be frozen solid by frosts but are still good to eat when they thaw. Often the clumps are small but occasionally Velvet Shanks turn up in profusion. Provided your specimens are young and fresh I find that their supposed toughness is overstated. Generally they are an ingredient, rather than a meal in themselves because of their small size.
Velvet Shanks are very recognisable because so few other fungi are fruiting (Judas’ Ears and Oyster Mushrooms being exceptions) but forage for them well outside the main mushroom season and check to make sure your specimens don’t have a hint of a ring, or they might not be what you think. If in doubt do not eat them.