Of air and water and light - solar halos over China

My flight to Japan was a remarkably comfortable one. Last week saw me in the sky for over 70 hours and thoughts of DVT played heavy on my mind as I got ready for the last leg of a rather mammoth few days. Days that I would however repeat, travel included, given the chance. Thankfully on changing at Amsterdam airport the ground staff took pity on my grizzled face and booked me into a seat with two spares next to it so I could finally stretch out.

I managed a couple of hours sleep on the 11 hour journey which is not a bad proportion for me, given that I normally manage none at all. After a recent flight where, on asking for a whiskey, I was presented with a good half pint of the stuff, I have been staying away from alcohol on flights. The whiskey did knock me out, but it also gave me a horrendous hangover for the waking hours of the journey.

Anyway, I was up to watch the sunrise over China and managed to see the faintest of green flashes, though sadly didn't get it on camera this time.

Later on in the flight however as we neared Japan the air at 30,000+ ft became filled with ice clouds and the interplay of light and ice made for a truly spectacular display.

The conditions were very interesting. Around the plane was a thin layer of cirrus clouds, with a high density of ice crystals, and below us where much thicker clouds, also packed full of ice crystals, many of them plate-like. Plate-like hexagonal ice crystals like to lie flat in the sky and act like mirrors to the sun. These are the crystals that cause sun pillars:

and sub-suns (the reflection of the sun off ice crystals in the clouds below):

This time however the display was a lot more complex. The column crystals in the clouds around us caused a 22 degree halo while the plate crystals gave a faint sundog (also known as a parhelion). In the thick clouds below however things got more interesting. The plate crystals below gave an effect that I'd never seen before. Not only did the light refract as it was passing through the sides of the crystals, but it also bounced off the bottom face, and back up, acting like a mirror to give a so called subparhelion. Moreover, because of the high density of crystals in the lower layers there was a strong 46 degree halo coming from a rather rare dynamic of light through the end of column crystals. It seems that this may not have been photographed before.

Here is the almost undoctored photo:

and here is a rather more doctored one just to enhance the effect to see the different arcs more clearly:

The reason that the circle around the sun is so distorted is because it's from the edge of a very wide-angle lens (Sigma 10-20mm at 10mm).

I sent this through to Les at Atopics who has been my source of knowledge and inspiration in the subject over the last few years and he sent me back a ray-trace computer simulation of what was going on. This is the simulation of the particular conditions so you can compare with the images above (click to view the full image):

The 46 degree arc in the clouds below seems to be an extremely rare event and the infralateral arc is also something rather special. All in all one of the best halo displays I've ever seen.

I've seen halo displays a few dozen times when flying now. Take some sunglasses with you, look out the plane and see if you can spot them next time...they're are there to be marveled at.

Now in Japan for the next 3 weeks. 2 weeks at a machine learning summer school and then a few days at the Yukawa institute where I will be giving a talk and hopefully chatting with some of the experts on entanglement entropy in holography. There are some ideas I need to talk with them about...

First day in Munich

Well, apart from 11 hours in the office spending lots of time chatting physics, I was witness to a partial solar eclipse, a 22 degree solar halo, an upper tangent arc and a circumzenithal arc. I only have the first three on camera, but I can promise that the fourth was spectacular. Most of the time the solar halo was completely behind clouds this morning, but I was able to get this one shot. Not the greatest shot ever (and NOTHING compared to this), but still:

and a half hour later, the cirrus clouds came in and I had a ten minute slot of this wonderful 22 degree halo and upper tangent arc:

Interestingly, there doesn't seem to be any reflection of the halo in the window on the right, which could be related to the polarisation of the reflected light, and the surface of the window.

When going for lunch later, the Cheshire Cat halo was out, but my camera was not. Still, not bad for the first day in Munich!

A little light and magic

(written mostly on Sunday)

It's been a funny old weekend, and I'm pleased to say that after the last post I've spent a lot of time walking around the city with less worry, but almost as much caution, as I had before.

Saturday was another spectacularly sunny day and I made my way towards town in one of the local mini-buses, packed in with 25 others, as the driver tore through the streets and his friend called out and whistled to passersby seeing if we couldn't shove another half a dozen people in the back. We passed an area that I'd heard of before, so I called and jumped off the bus, and started wondering Woodstock, a pretty rundown neighbourhood, but one which I'd heard had hidden treasures. It didn't take long to find the old biscuit mill, which now, every Saturday, plays host to a fantastic food market, with delicacies made freshly but originating from around the world. I tucked into a great smoked salmon in rice paper wrap and wonderful seared swordfish with passion fruit and avocado. I also got the first decent cup of coffee I've drunk whilst in Cape Town before tearing my way away from the food tents and walking around the extremely artsy-looking home-stores, clothes shops and photography galleries.

I took another treacherous journey in a local minibus (here called taxis) into the centre of the city and wandered around the rather unappealing looking streets until I found a nice square to bask in the sun, read a book and work out my next move.

Though they may seem overly touristy, I've started using the open-topped bus tours as a way to get to know a city if given only a short time in it. The two hour tour took me through most of the important districts in the city, including the infamous District 6, up to the cable station of Table Mountain and on around the beaches to the West where the rich and famous sun themselves. I took this from round the corner of one of the most exclusive areas to live in Cape Town:

Getting back to the small but rather historic guest house, I met the owner and her daughter, whose boyfriend was there with an old school friend of his and his girlfriend. Soon another guest arrived, and on inspection I found myself to be in the company of an international rugby star, a world famous paleontologist and a TV star/top model/DJ. We chatted for a while and watched the rugby which was being played down the road, before I headed off to get something to eat in one of the local restaurants. I didn't manage to explain my thoughts on the holographic principle to the model, though I have no doubt that she would have been fascinated!

Sunday I headed off for a walk in the forest at the foot of Table Mountain which boasts one of the most diverse ecosystems in the world. It's a really stunning area with such a variety of ancient flora (mostly being made of of a plethora of ferns) that you seem to be moving from one continent to another as you walk through the undergrowth.

Getting out of the forest we headed to Montebello's, one of the areas famed lunch venues and sated our appetites on a strange sushi rice based concoction, wasabi'd to perfection, before heading back to the guest house. I spent the afternoon getting on with work and chilling into the evening.

The rest of the week so far has been a push on the project which has taken a few u-turns but we have some concrete calculations to look at for now. Today was a bit of a break as I gave my talk on atmospheric optics as a departmental colloquium. I had a good reception and the number of questions after and display of photos with a variety of cloud formations and optical effects which people quizzed me with was a great sign. I'll be happy to give this in other departments in the future and it looks like I have one lined up for Chile in August.

In fact the weather played its part today as we had a rather lovely solar halo over the campus through the morning (and now a fine lunar halo). I played my usual part and pointed it out to random passersby who gave me a much warmer reaction than that which I've received in any other country. It's not the greatest solar halo ever, but it is the best timed!

This on the other hand is a mystery to me. As I headed out of the department on Monday I was greeted with a strange light around the top of Table Mountain which stayed pretty stationary, though faded as the clouds moved swiftly across the peaks. Within five minutes it was gone, but I have a feeling it was as much to do with the position of the sun as the cloud formation. My only guess is that there may have been two layers of lenticular clouds which let through a perfect sliver of light. Any other suggestions would be gratefully received.

This, by the way, is the magnificent campus view of Table Mountain (actually Devil's peak) directly behind the main UCT hall.

Everything under the sun

Having not stepped foot in the British Isles for more than a few hours since February, there have been a few changes over these last months. The streets of Oxford have their transient shops, going through waves of success and failure, and changing week on week, but despite the new facades it feels something like home. I count myself as lucky that while I don't currently feel I have a place to call home (knowing that at each stage of my journey I will, sooner rather than later, be moving on somewhere else), I actually feel quite at ease in this state of fluidity.

I spent today back in the centre of Oxford working in a couple of cafes before coming home to tea and mince pies to continue study. I have two more projects that we would like to finish before Christmas and these will keep me out of trouble for the coming weeks.

Thankfully television is no distraction. In my hotel in Dublin I made the mistake of turning on the TV (the first time I've seen television in many many months) and realised that I'm so out of touch with British pop culture that I have no idea who any of the "celebrities" on the unending, jaw-droppingly bad reality TV shows are. Such ignorance fills me with more than a little pride.

I don't have a raft of exciting tales to tell from Dublin, though yet again this charming, if outrageously expensive city brought several days of enjoyment, both through plenty of scientific discussion, the odd guinness and a little time to tour the city. On an icy cold Saturday I sat atop an open-air bus to see the city, something that I can highly recommend if you have a short time to see somewhere you don't know well. Touristy though it appears, it's convenient, and unless you're reading up on the place before you arrive, you're likely to learn a great deal whilst catching all the highlights.

Anyway, the only other tale to tell is of the flight over from Stansted to Dublin where, above the murky cloud-line I was greeted with another wonderful halo display, this time witnessing my first ever sub-sun as the light reflected of the plate crystals in the clouds below us. Seated over the wing (in order to take advantage of the leg-room) I missed out on any possible Subparhelia but caught a few glimpses of sundogs, changing quickly as we passed layers of cirrus clouds.

Bright subsun:

22 degree halo with sundog:

and 22 degree halo with subsun tangent arc:

As always consult atoptics for the full explanation of these phenomena.

Life in a 22 degree arc

Lots to do this weekend so not much time to write but I'll simply post a picture of a solar halo that appeared as I was on my way to work a few days back. An HDRified take on the scene taken with the new lens I got a couple of months ago. With my 17-85mm Canon lens I can just fit a 22 halo into the screen, but with the 10mm lens in fits in with acres to spare! Yet again I stood there contemplating for a good quarter of an hour with passersby not wondering for a moment what I might be staring at....I despair!

Total solar eclipse in Wuhan, July 22nd 2009

I spent a frantic few days in Shanghai trying to find where and when the tropical storm was going to hit the city. Two things quickly became clear: one was that the weather websites hadn't predicted a single day correctly in the previous two weeks, and the second was that the skies of Shanghai sure seemed to be clouding up fast.

Searching for satellite data, other eclipse hunter's predictions and any weather website I could get my hands on it seemed that the best bet was going to be to head West to Wuhan. Wuhan sits around 1000 km to the West but luckily the transport system in China is remarkably good. Catching the train on the afternoon the day before the eclipse gave me not only a pretty comfortable five hour ride to the city, but also the chance to meet some fellow eclipse hunters. John, from Germany, stuck out from the crowd with bags bulging with camera equipment, videos, filters and tripods, making my single camera and solar filter rigged up from a Pringles packet look somewhat ridiculous (I did at least have a Manfrotto tripod to give me a little more credibility). John was travelling with May, who works in Shanghai but is originally from Wuhan. In addition were a couple of American TV producers who were in the country for a week or so hunting for this, the longest eclipse of the 21st century.

We got into Wuhan and all made our way to a hotel right next to Huang He Lou, the yellow crane tower, and what I thought would be a good spot to see the eclipse from. Getting a bite to eat the night before in an outdoor food market gave me a chance to indulge in some stinky tofu and an excellent dish of spicy pork before heading to bed.

I hadn't slept more than a couple of hours the night before, worrying about where I could see the eclipse from, and that night too I couldn't sleep for the expectation of what we may see the next day. Arriving into Wuhan the skies were clear and at night the stars came out, or at least attempted to poke through the light pollution of the city of ten million.

So, a little bleary eyed, but very excited we met at 6.30 the next morning to get ourselves ready for the event with plenty of time to find a position and set up shop.

Walking out of the hotel I looked up to the sun and was greeted by a wonderful morning solar halo, a fine view indeed, but a sure sign of some cirrus clouds joining us for the show.

We walked up to the temple and found a large crowd, equipped with eclipse glasses who had had the same idea. At 7.30 we were all let in and rushed around to vie for the best spots. John, the seasoned eclipse hunter discovered the best place and we set up our equipment, waiting for the first signs of occlusion.

While setting up my kit I was greeted by a never ending stream of reporters, keen to chat to the only Chinese speaking foreigner and I was asked the same dozen question for an equal number of newspapers. At one point I was also interviewed for TV but sadly shied away from giving the interview in Chinese.

As the time grew closer, the clouds moved in and it was clear that we were not going to have an easy ride. Indeed as we approached the moments before totality the clouds thickened and we were left with only a few glimpses through the patchy cloud of totality itself. I managed a few photos of the sun as the moon gradually moved across the face but it turned out to be very hard to find the sun with a zoom lens and a strong solar filter when the sun is partially blocked by clouds. The solar filter is so strong that only an unobscured sun is clearly visible. Still, I got a few shots and these were perhaps the best couple.

For totality itself the crowds around cheered as the sky darkened completely, lit only by the horizon where totality was not apparent. They seemed happy enough with the darkness and were not sad at the lack of the spectacular corona. I did my best and got a couple of shots with the zoom before changing lenses and taking in some wider angle shots to include the temple itself. I have a series of 20 or so shots which I will make into an animation as soon as possible. In the mean time, here are my efforts from the moments of totality, clouds included. These were from the clearest ten seconds or so of the five minute totality.

It was a strange mix of excitement and disappointment, mixed with not a little amusement, knowing that I'm probably one of the few people in the world who has seen three cloudy solar eclipses in a row. I will of course keep on hunting, and though I may not make it to the next showing in the Easter Islands, I'll be on the case before too long.

A little haloey goodness for Earth day

The sky over Santiago is awash with cirrus clouds these days giving almost daily halos in some form or another. Yesterday there was a lovely sun dog at sunset while today all through the afternoon we had an almost perfect 22 degree halo, with a small circumscribed arc to boot:

Keep an eye out, you never know quite what you're going to see!

22 degree solar halo redux

Just before I head off in a few hours, I put the halo photo taken with a circular polariser through a tone-mapper and came up with this, I think the best of the current lot in terms of how accurate a portrayal it is of the real thing:

22 degree solar halo + circumscribed halo over Santiago de Compostela

As promised, photos of the solar halo over Santiago earlier today. The sun was up at around 52 degrees and in fact there was a faint circumsribed halo around the 22 degree halo. This could only be made out faintly with the naked eye, but with a bit of post-processing is quite detectable on screen.

Anyway, these were my photos from today. First, a shot using a circular polarising filter to bring out the contrast:

Second, without the polarising filter, a little earlier one could see the circumscribed halo faintly:

and thirdly with some strong post processing, the cicumsribed halo is strongly visible:

Again, people walking nearby could see me pointing up to the sky with a camera, and didn't wonder what I was looking at. I do find human beings who are supposed to be curious animals to be so tied up in their own little worlds and uninterested in the phenomena around them. I did at least manage to get a couple of people to see it who seemed happy at the distraction.

Halo spotters in Galicia....

There's currently a really stunning 22 degree halo which can be seen from Santiago de Compostela. I'll post some photos later, but from the current cloud speed and structure I would guess it's going to be on and off for a few hours yet.

Anyone else see it, try and get some photos and I'd love to see them.

Atmospheric optics picture of the day

I posted about the wonderful solar halo display over Porto last autumn. Of course I sent my photos to atoptics and got an excited response that I may have captured a rather rare display. After much analysis of my large set of photos the good news is that indeed I was lucky enough to see a full display of Lowitz arcs. The pictures and description are up online at atoptics now as the picture of the day.

Stunning solar halo over Porto

From ice and sunlight amazing things will come...

I'm going to do a full Porto blogpost soon, but I needed to get this out before anything else, as anyone who knows me will understand.

Sunday afternoon I was in the gardens of a wonderful modern art museum in Porto (Serralves), walking around and taking in the sun with a friend of my couchsurfing host.I looked up, as I seem to spend most of my time doing and caught a glimpse of a solar halo beginning to form. We got out into an open area and watched as the upper arc of the solar halo turned into the most stunning display I've ever seen.

As the field of ice in the clouds swept across the sun, for around half an hour the sky was illuminated with the most stunning arcs, halos, sundogs and perhelia I could imagine. Of course I got a ridiculous number of photos of this and have only gone through some of them in detail. In particular it appears that the pictures of the sundog may have captured a phenomenon rarely captured on film. As explained to me by the author of the superb site atoptics when I sent him the photos:

'...But something about your image caught my eye. I then severely enhanced it and have attached the result. It looks to me as though you have the very rare Lowitz arcs and have unusually captured the upper, lower and middle Lowitz components. See the very first Lowitz image for comparison..' This effect was first captured here, but it seems possible that I may have caught it too.

On top of the 22 degree halo, the upper tangent arc and the sundog, there was a lovely 120 degree parhelion, something I'd never seen before. Having spent some time reading atoptics in the past I had a good idea where each of these effects was coming from and to see them so vividly was wonderful! Each part of the pattern comes from a particular shape of ice crystal with a given orientation and a specific path of light, sometimes through the faces and sometimes through the edges.

Of course I told those around me about the amazing display in the sky but all but two of them showed no interest at all, looking up and then seeming rather surprised that I'd bothered them about it.

Anyway, here are a few of the pictures I took of this startling sight:

The upper tangent arc, the 22 degree halo and the sundog:

The halo, the sundog and the parhelic circle:

The sundog, the parhelic circle and the 120 degree parhelion:

and the 120 degree parhelion shining brightly. It seems that as noted occasionally before, this has a faint redish tinge to it (only seen on the zooms):

All of the above images can be seen in larger sizes by clicking. There are also currently a great number more photos on my flickr account as I've simply dumped them up there for now for further analysis.

I have mixed emotions about this. On the one hand I was overwhelmed with the sight, grinning and running around like a kid in a sweet shop for half an hour, while on the other I'm saddened by the lack of interest most people have in the wonders of nature. Still, in a few weeks I will be doing my bit by giving a lecture to the whole physics department on atmospheric optics. I hope to get another few people enthused by what is out there!

Solar halo over Seoul

A tiring but enjoyable day today, doing a bit of sightseeing around Seoul, I headed to the hill where the Northern Seoul tower is based, which turns out to be quite a trek in the midday heat. The view from the top gives a good sense of scale of this metropolitan area with a population of some 23 million people, pretty big, even by Chinese standards! The North mountain, Namsan houses not only the tower, but a host of other cultural exhibits and museums, and is worth a couple of hours wondering around. The forest leading to the top is also a rather pleasant change from the nearby buzz of the city.

Up at the top I was greeted with another solar halo, though only partial this time (click on the solar halo tag below this post to see more halos I've previously taken). Still, always a beautiful sight. Sadly I couldn't get to the right angle to get the tower with the halo, so opted for this simple view instead:

Apart from wondering around another of the temple complexes, it's been a relatively quiet weekend, in the knowledge that I don't have so much time to work here and still with plenty to do, yesterday was spent trying to get some ideas and calculations ready for tomorrow. It's going to be a busy week in the office, but, I hope, a productive one.

Synchronicity in Paris!

For me photography is still about those lucky moments where you're in the right place at the right time. However, it's also to a large extent about noticing those moments that most people don't. I'm still shaking from the excitement yesterday of being at the scene of something truly spectacular, and incredibly of being the only person with their jaw dropping at the incredible thing in front of my eyes. Anyway, words don't do it justice! This is a 22 degree solar halo in perhaps the top place in the world I would have hoped to see one!

This was a six photo panorama, which especially hard to get right when you're dribbling with excitement :-)

Go to Atmospherics Optics for a great explanation of this phenomenon.

Also see here for more of my photos of this.