Early this week attention focused on the first storm named by the Met Office and Met Eirann. “Abigail” was a typical winter Atlantic storm, one of many which would be expected to impact on the British Isles each year. The reason for naming storms is explained:
As the UK and Ireland’s National Met Services, the Met Office and Met Éireann operate to maintain public safety through severe weather warnings and forecasts. Working together, it is hoped that naming storms will help raise awareness of severe weather and ensure greater safety of the public. The Met Office and Met Éireann will continue to issue weather warnings in the normal way using the Met Office National Severe Weather Warning Service and Met Éireann Weather Warnings. A storm will then be named when it is deemed to have the potential to cause substantial impacts in the UK and/or Ireland. To avoid any confusion over naming, if a storm is the remnants of a tropical storm or hurricane that has moved across the Atlantic, the already established method of referring to it as, e.g. ‘Ex-hurricane X’ will continue.
Abigail brought strong winds and some disruption to Scotland and parts of Ireland, along with heavy rain. Here, in southern England, it was nothing unusual for November: breezy and wet.
This system has brought huge amounts of rain to the north and West of the country, especially Wales. This rain has been heaviest where the air has been forced up by terrain (“orographic” rainfall) and has been heavy enough to cause significant flooding. Again, here in the south of England, things have not been too unusual. We had light but very persistent rain for many hours yesterday, giving a total of about 10mm. It is also rather mild for the time of year as we experience a warm, wet tropical airmass. Today it is breezy, but nothing extreme.
As the system rolls through into Europe, it looks as if cooler polar air will be pulled down across the British Isles behind it, with temperatures likely to fall to seasonal norms, for the first time this autumn. November so far has been about 5C above the long term average for this location.
A new meteor shower has been (provisionally) recognised and my meteor camera is playing a small part. Firstly, meteor observers around the world received a request that we should carefully check our data following a report of an “outburst”. This is not as spectacular as it sounds, simply that observers had noticed a number of meteors from the same part of the sky – too many to occur by chance.
P. Jenniskens, SETI Institute, reports the detection of an outburst from
a new Jupiter-family comet shower, the chi Cygnids (given IAU number 757 and
abbreviation CCY). Martin Breukers and Carl Johannink first noticed five
nearly identical orbits in multi-station video observations of the CAMS
BeNeLux network in the observing interval Sept. 14d19h23m-15d03h35m UT.
Partial results from the CAMS California network add four meteors in the
observing interval Sept. 15d03h10m-15d12h45m. The nine meteors detected
appeared between Sept. 14d21h and 15d11h UT (solar longitude 171.54-172.08
deg). The geocentric radiant is at R.A. = 301.0 +/- 2.2 deg, Decl. =
+32.6 +/- 1.6 deg (equinox 2000.0), with velocity v_g = 15.1 +/- 0.9 km/s.
The median orbital elements are (N = 9): q = 0.949 +/- 0.003 AU, a = 2.75
+/- 0.40 AU, e = 0.655 +/- 0.041, i = 18.6 +/- 1.6 deg, Peri. = 209.9 +/-
1.9 deg, Node = 171.64 +/- 0.23 deg (equinox 2000.0).
Confirmation of the outburst was found in the near-real time CMOR radar
observations (P. Brown et al., University of Western Ontario), which are
posted at website URL http://fireballs.ndc.nasa.gov/cmor-radiants/. The
24-hr averaged maps showed a small concentration of radiants at this
position during the observing period 15d05h15m-15d20h15m UT.
We were asked to analyse and send in video observations from around 15 September. I had already sent mine. Jakub Koukal (from the Czech Republic, who co-ordinates EDMOND the European database of meteor observations) then sent an email to Richard, another member of UKMON:
… now i have one orbit of 757CCY (20150914_202235) between your east camera (Wilcot E) and Horley SE. After collecting all data, it will be time for recalculating elements. I found overall 51 orbits in EDMOND database from year 2007, with another outburst in 2010. This means that this shower is annual, with low activity between returns of potential parent body (comet from Jupiter´s family), and with outburst during perihelion passage of potential parent body (~5 years) – something like Draconids or Leonids. In attachment is confirmation (provisional) of this shower, based on current data, which i have.
It looks as if the Chi Cygnids is a small meteor shower which peaks every five years to coincide with the return of an (as yet unidentified) comet which leaves debris in its orbit. If this is eventually confirmed, one meteor observation from my camera will be among a hundred or so which were used to identify the shower.
New meteor showers are being recognised all the time, partly as a result of good data from observations made with simple video equipment. It is a minor discovery. It will not change the world, but in a tiny way, has changed our understanding of it. I am pleased to have been part of real science, with lots of other amateurs and a few professionals co-operating around the world. That’s quite a good feeling!
I stepped outside to watch the International Space Station pass over. I love to watch it. Its stately movement across the sky is beautiful, and thinking about what it means is important, I think. As it moved away eastwards I saw the sudden flash of a bright perseid meteor below it. This was a classic perseid. Blue colour and with a little explosion at the end. All over in a moment, but lovely.
I was pleased to find that my meteor camera had caught it, so I could make a video to share at least a little of the experience.
The meteor camera I operate caught an unusually slow and long-lasting meteor at 00:18 on 1 August 2015. You can see what the camera saw in the video. Although the camera is noisy and grainy (it is cheap, basic, but sensitive CCTV camera) it gives a great sense of the meteor sweeping right across the sky (actually about 60 degrees).
The meteor was also captured by several cameras in the UK Meteor Network and at least one in Nemetode, so the orbit can be calculated. It looks as if the meteoroid (the object in space before it hits the earth’s atmosphere and becomes a meteor) orbited between the orbits of Mars and the Earth. It was probably small, like a sand grain. It would have been completely burnt up in the heat of entry to earth’s atmosphere. It was travelling at about 6km per second or 21,600 kph (roughly 13,400 mph) so would have heated up very quickly as it hit the upper atmosphere.
It also looked beautiful through the clouds: a classic “shooting star”. The video is in real time. The meteor was roughly magnitude 0.7: similar to one of the bright stars but not the brightest thing in the sky and much less bright than many meteors.
The Sun has reached its highest point in the sky, marking the beginning of astronomical summer and the longest day of the year. Solstice means “standing still” – a day when the path of the Sun across the sky does not appear to be moving up or down.
From now until 21 December, the Sun’s path will appear to move closer to the horizon and days will become shorter. This will happen in small amounts (a few minutes) especially at first, but the nights are already drawing in.
The atmosphere and oceans take time to warm up, so this is not usually the warmest part of the year, which is still to come.
We are coming into the season of “white nights” around the summer solstice, when there is no true darkness because the sun is close below the horizon still illuminating the atmosphere even though the sun itself is not visible. In effect, the sun has started rising as soon as it has finished setting. Of course, if you were to travel further north, this phenomenon is clearer and more dramatic until, at the arctic circle, there are times when the sun does not set at all. We are at 51 degrees North here and the Arctic Circle is roughly 66.5 degrees North so we are about 930 miles (1,722km) short of the midnight sun, which is not that far compared with the size of the Earth.
There are degrees of darkness. We tend to call darkness that is not complete “twilight”. Civil twilight is when the sun is 6 degrees (or a little more than the width of a hand held at arms length) below the horizon. The horizon is clearly visible as are objects (such as mountains) even though, on a very clear night, the brightest stars are becoming apparent. Nautical Twilight is when the sun is 12 degrees below the horizon. The horizon is no longer clear although some objects may be discerned. Astronomical twilight is when the sun is more than 18 degrees below the horizon – complete darkness (apart from light pollution, of course)
Around the summer solstice here, we have a few weeks where there is no astronomical darkness. This is well shown on the “skylight clock” on the weather station web site.
Yellow is daylight with the sun above the horizon, the light blue is civil twilight, (sunset until the sun reaches 6 degrees below the horizon or from that point until sunrise), the mid blue is nautical twilight (sun reaching 12 degrees below the horizon) and the dark blue is astronomical twilight (the sun reaches 18 degrees below the horizon). Black is darkness. The red hand indicates what time it is relative to this. At the time of writing, there is a sliver of black left on the clock, but this will soon disappear until the evenings begin (slowly) to draw out in July.
All this affects nature. Animals (and small children) go to sleep later and get up earlier. Most British animals are crepuscular: being most active through twilight and in the morning and evening. As people tend to stick to the clock, we miss their most active times through this period of the year. perhaps we should get up and go to bed with the sun, but have a sleep in the day at this time of year!
Early this morning (22 Feb 2015) my camera recorded two bright meteors. These are not connected, but it after weeks of cloudy skies and very little activity when it was clear (this is the quietest time of the year for meteors) it is nice to have captured two impressive meteors.
The first was at 00:28 (UTC). This is probably a February Eta Draconid meteor (see here for details of this recently discovered meteor shower) and had a magnitude of -3.4 making it about the brightest thing in the sky. The path appears to be curved because of the wide angle lens in the camera. In fact, the meteor passed almost overhead here – its path started above the North Downs and ended over the South Coast. It was still probably about 35km high when it burnt out.
The second came in at 03:39 and was a sporadic – not associated with any known meteor stream. It had a magnitude of -2.9:
Both meteors show a small explosion during their path.
Songs allow birds to mark out a territory, which protects the resources they need to breed. The song is a challenge to other birds of the same species, but also prevents conflict because birds who do not wish to challenge for the territory can avoid it. Peak activity for birdsong in our climate is crepuscular – in the time around and after dawn and again in the evening. The dawn (and dusk) chorus, where birds of many species sing, is one of the glories of nature and one of the most powerful signs of spring.
It is rather difficult to pinpoint when birdsong begins again. Robins, for example, sing a little all through winter. It is a sound of hope in the darkness and also reflects that Robins maintain a territory through the winter. Some species will begin to sing in mild weather, but stop again if the weather worsens.
This year, the first day I heard a substantial amount of bird song was on 27 January. I noted that not only did I hear a Robin, but that there was a great tit (whose song is very monotonous) and several blackbirds singing in the dusk. In 2014, I experienced something similar on 8th January – weeks earlier. It was much milder in 2014, of course.
Last week, here and at College on the South Downs, there were a couple of days with lots of birdsong, which I am hearing much better now I have hearing aids to help with high frequencies. There were lots of thrushes singing at College – quite wonderful.
The weather station began to operate in August so I do not have data on a full year yet, but I thought it might be useful to mention a few figures.
The highest temperature was 27.2C at 15:00 on 18 September and the coldest was -5.1C at 07:33 on 31 December. 18 September was the only day when the temperature was above 27C (or 80F). The highest minimum was 15.9C on 6 August ( an uncomfortably warm night) There were 13 air frosts (2 in November and 11 in December)
The strongest gust of wind was 47kts (54mph or 87kph) at 03:41 on 12 December. December was the windiest month too.
It rained on 82 days (out of 153 recorded days). Six of these days had more than 20mm rain and 49 more than 2mm (which is what most people would notice as “raining”). November was the wettest month with 156mm, but October was close behind with 147mm. The wettest day was 23 November with 29.6mm.
My meteor video system captured sprites early on the morning of 8 November 2014.
Sprites are one form of transient luminous event or upper atmospheric lightning. In the upper atmosphere, very high above active thunderstorms, there are various forms of electrical discharge (sprites, elves, blue jets and even gnomes and pixies!) that are poorly understood and which were not even recognised until the last 20 years or so. In the last few years, it has been realised that video systems designed to capture meteors may also capture these fleeting phenomena which seem to occur at similar heights to meteors. Early this morning, my meteor camera caught two (and possibly three) sprites associated with thunderstorms that were over Northern France and the English Channel (120 – 150km away from here) at the time. I am thrilled to have video of one of the atmosphere’s most elusive sights.
At 03:20 the system captured a “columnar sprite” or possibly a “blue jet” (Clearly visible in the lower centre of the image captured from the video). As I look at the video in detail (frame by frame) I can see a very faint general flash along the lower right of the screen one frame (1/25 second) before the sprite appears. I think this was the very distant lightning reflected in clouds that were just below the horizon here and possibly from some clouds that are just visible in the image, between here and the storm. (The video camera is extremely sensitive, so this seems possible. Lightning is easily bright enough to be seen from 150km away at night if you are high enough. I was once thrilled to watch from the window of an airliner at night as lightning coursed backwards and forwards through a line of towering African thunderstorms. The captain reassured us that we were over 100miles away from them). The sprite lasts three video frames or 3/25th second, with only one frame being bright as shown in the image. A blue jet is emitted from the top of the thunderstorm cloud, so this is more likely to be a column sprite – an emission high in the upper atmosphere (perhaps up to 100km) above the storm.
The video shows a very much fainter sprite happening about 1/5 second before this one, to its left and lower down.
At 03:37 (see main image) the system captured a classic “carrot” sprite – very clear and bright. Again, it is possible to see a brightening along the horizon, which I assume to be from lightning, about 1/25 second before the sprite appears. This sprite appears on four video frames (4/25 second in total). The central column appears first then the “carrot”. Like lightning, sprites are a very short lived phenomenon.
Such sensitive video systems are very noisy – the backgrounds look like snowstorms, and trying to convert the video to web format makes it even worse. I will try to process a viewable video and share it. On my computer, it is possible to work through frame by frame to see the details. The sprites are fairly bright. If you had been looking in exactly the right place (and had you eyes open and focused at the split second the sprites occurred) you could have seen them with the naked eye.
I have reported the sprites to researchers at Bath University, as well as to the UK meteor network.