Potten End Newsletter Article 4

This article originally appeared in the Potten End Newsletter, September 2012.

Potten End Skies

From Meteorology to Meteors and Beyond!

A slight change of course in this issue takes us from meteorology to meteors and beyond.
We’re lucky to have relatively dark skies in Potten End. Free from the pollution of excessive lights, the skies are dark enough to view lots of interesting celestial objects that town and city dwellers will sadly miss.

Meteors or shooting stars are not as rare as you might imagine. Spend half an hour looking up at a clear night sky and you’ll often see a couple in the corner of your eye. You have to be lucky to see them directly as they pass very rapidly. It’s a little late to see the Perseid meteor shower that peaks every year between the 9th and 14th of August but this year the skies were slightly overcast during the critical time so you haven’t missed much. In perfect conditions the Perseid meteor shower can be quite spectacular as it produces over 100 visible meteors an hour with colours ranging from pale yellow to orange and blue.

Meteors are caused by small particles of debris (ranging from dust to the size of a small pebble) burning up in the atmosphere between 75km and 100km above the Earth leaving a visible trail of hot gases and melted meteoroid particles. The Perseid meteor shower is caused by dust particles from the tail of the Swift-Tuttle comet entering Earth’s atmosphere at around 132,000 miles per second.
Regular meteor showers are named after the area in the sky from which they appear to originate. The Perseid meteors appear to radiate from the constellation in the North East named after the Greek hero Perseus, and have been regularly observed for at least 2,000 years with the first written observations made in 36 AD in the Far East.

The next meteor showers to look out for are:

• the Orionids from October 20th to the 24th which should produce about 20 pale yellow and blue meteors an hour.
• the Leonids from November 17th to the 18th which should produce about 40 pale yellow and blue meteors an hour.
• the Geminids from December 13th to the 14th which should produce about 60 multi-coloured meteors an hour.

September has a few interesting celestial events. The equinox (when night and day time are equal) occurs on 22nd September. The days start getting shorter from that point. The full moon closest to the equinox is called the Harvest Moon and that happens on September 30th. It’s called the Harvest Moon because the light from the full moon allowed farmers to work longer hours in the fields in the autumn.

The International Space Station (ISS) will be visible towards the end of September. You can hardly miss it as it is extremely bright and fast moving – quite different to a high flying jet plane or a satellite – but you’ll have to be up and about very early in the morning to see it.

I’m hoping for better weather and clearer night skies in the weeks ahead, but all long range forecasts continue to indicate unsettled weather for the foreseeable future. However it’s worth taking a long look at the night sky whenever you get the time. There’s always a chance of seeing something truly awe-inspiring.

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“Look up at the stars and not down at your feet”
Professor Stephen Hawking,
London Paralympic Opening Ceremony 2012.

Potten End Newsletter Article 3

This article originally appeared in the Potten End Newsletter, July 2012.

Potten End Weather

There are an enormous number of old wives tales and country sayings that relate to the weather. Some of them are complete hogwash, but many of them have a basis in scientific truth.

Perhaps the most common, “Red sky at night, shepherd’s delight. Red sky in the morning, shepherd’s warning” is older than you might think and even appears in the Bible (Matthew 16) from as early as 1395. Undoubtedly the saying originated significantly earlier than that.

There is a scientific explanation behind the saying. When the sun is close to the horizon both at dawn and dusk, the sunlight travels to us through more atmosphere than at other times of the day. The red light is able to travel a more direct course and reflects off clouds giving a red sunrise or sunset. Bluer light is more scattered and less of it is reflected from the clouds.

In the UK and in the northern hemisphere in general, weather predominantly comes from the west. If red light is reflected off the clouds in the morning then those clouds are probably headed our way bringing with them an increased chance of rain. And if we see red clouds at night, then the chances are that the clouds have already passed us and we’re in for a nice day tomorrow.

The Rain in June

“And when it rains on your parade, look up rather than down.
Without the rain, there would be no rainbow.”
G. K. Chesterton.

From the weather archives, the average rainfall for the month of June is 38.4mm. The last measurement for June before publication showed we had 128mm of rain (333% more than local average) and the indications were that more was on the way.

So why are we still in a drought according to our local water company? The reason is that Veolia Central take most of their water from underground. They say that “Following two years of very dry weather before April, our groundwater levels remain very low.”

Because most rainfall in the spring and summer is either absorbed by plants or is lost to evaporation, very little of the rain makes it to the aquifers. However, we’ve had exceptional rainfall recently and the good news currently is that the aquifers are starting to fill up. They are still at a “Notably low” level according to the Environment Agency, but at least that’s one level up from the “Exceptionally low” level that they were at a couple of weeks ago.

At least the garden isn’t suffering too much from the hosepipe ban at the moment.

June Rain Compared to the Average

From our short-term records (only going back to 2006), the average rainfall for June is 38.4mm.

By the 5th of June, we’d just passed the monthly average.

By the 11th of June, we’d had twice the monthly average.

By the 15th of June, we’d had three times the monthly average.

At the time of writing we’ve had 130mm of rain and are expecting heavy overnight rain.

Update 1pm, 24th June: We’ve had another 16mm of rain overnight and this morning bringing the monthly total to 146mm.

Four times the monthly average (153.6mm) seems quite reachable at this time. Especially as Wimbledon is imminent.

Drought Situation – June Update …

A quick update to this post: We’ve now had a total of 116mm rain this June.

A glimmer of hope on the hosepipe ban horizon: One of the three aquifers that our local water company uses has risen from “Exceptionally Low” status to  “Notably Low”. This is an indication that some of the rain is getting through to the underground reservoirs.

See the weekly water situation report here: http://www.environment-agency.gov.uk/static/documents/Research/WE_120612(2).pdf

The Environment Agency are due to publish a new weekly water situation report  in the next day or so. Watch this space.

Record Rainfall for June …

… and it’s not over yet!
  

June	Rain Total
2012	105mm
2011	81mm
2010	22mm
2009	57mm
2008	21mm
2007	11mm

From our records, the monthly average rainfall for June is 38.4mm. As I write this it’s the evening of the 12th of June and in these 12 days we’ve had 105mm of rain so far! That’s over 270% of the average.

Forecasts for the foreseeable future (around 5 days) show more rain is on the way. Longer range forecasts, though far less accurate, predict a continuing grim remainder of June with temperatures below average and still more rain.

End to the Hosepipe Ban?

So is there an end to the hosepipe ban in sight? Not according to our local water company (Veolia Central). Veolia Central take most of their water from unerground water sources and they say that “Following two years of very dry weather before April, our groundwater levels remain very low.”
Veolia Central add: “Unfortunately at present, we cannot relax the temporary use ban further, as we need to conserve our supplies to prepare for the possibility of a third dry autumn and winter.”

They go on to explain that most rainfall from April to September is absorbed by trees and other plants or is lost to evaporation, and that in order to move us out of a drought situation, we need “prolonged and substantial rainfall between October and March“.

So, unless Veolia Central’s measurements show that a lot of the rainfall in recent weeks has not been absorbed or evaporated, and that it has made it down to the underground reservoirs, then it looks like the hospipe ban will remain in place.

It’s not like the garden is suffering too much at the moment!

Increasing Trend

There also appears to be a general trend of increasing rain in June over the last few years. Sadly this corresponds to some theories about what will happen to the UK climate as global warming increases, but this is such a small statistical sample that no credible link can really be made.

June Rainfall from 2007 to 12th June 2012

Potten End Newsletter Article 2

A condensed version of this article originally appeared in a special commemorative edition of the Potten End Newsletter, June 2012. Also, there were some minor mathematical errors in the original article – they have been corrected here.

Potten End Weather

I’ve taken a bit of a departure from my planned series of articles to briefly write about the extraordinarily wet April we’ve just had.

Also, as this is a special commemorative issue of the Newsletter, I’ve been digging around in the weather archives of the Met Office and other sources to find out what the weather was like over 60 years ago.

The Wettest April on Record

The rain it raineth on the just
And also on the unjust fella;
But chiefly on the just, because
The unjust hath the just’s umbrella.
– Lord Bowen

The Met Office declared April 2012 the wettest since records began in 1910. And it certainly felt that way. In fact, our region of the UK received 237% more rain than the average April rainfall from 1971-2000.

How do our Potten End records compare to that? Well, we measured a total of 113mm of rain in April. This is the wettest April we have on record by quite some margin. Here are the rainfall totals for April in previous years:

• 2011: 8mm
• 2010: 12mm
• 2009: 20mm
• 2008: 45mm

And it rained every day from April 17th to the end of the month. The wettest day being Sunday 29th April with a total of 21mm falling that day.

Surprisingly, the sunshine amounts for April have not been far off the average.
Despite all that rain we’re still in drought conditions with a hosepipe ban because we still haven’t had enough rain in the east and south-east this year.

April has been in stark contrast to March, which was the fifth driest on record for the UK.

The Queen’s Weather

As this is the commemorative edition of the Newsletter, some have been wondering what the weather was like sixty years ago.

In February 1952 when Queen Elizabeth II was proclaimed Queen, the month started out mild and dry, but became grey and a little wet towards the end. It was the driest February compared to the surrounding years with only 11mm of rain that month. In February 1951, 121mm of rain was recorded.

In 1953, the month before the Coronation had been dry and warm with temperatures reaching nearly 32C in the week before the actual event. But the weather turned at the end of May and the day of the Coronation was decidedly cold, grey and wet. Though it did dry out in the afternoon, the high temperature was only 12C.

And This Year?

Because of the lead time in producing articles for the Newsletter, it is not possible to provide meaningful forecasts for the Queen’s Diamond Jubilee bank holiday. All long range forecasts tend to be very vague with a lot of wriggle room. Depending on where you look and how you interpret trends, the weather will always be some combination of hot, windy, wet, cold and dry.

As an example of just how variable long range forecasts can be, here are just some of the forecasts at the time of going to press:

There are indications that a high pressure zone will develop to the north of the UK which could mean a westerly or south-westerly flow will bring changeable conditions resulting in a ridge of high pressure which could bring some pleasant weather. On the other hand that could also mean that low pressure systems will be forced to take a more southerly track resulting in prolonged wet weather.
My favourite prediction is that the high pressure zone extends and moves south causing warm air to be pulled up from Africa or southern Europe. This gives rise to the effect known as the “Spanish Plume” heat wave. Olé!

Potten End Newsletter Article 1

This article originally appeared in the Potten End Newsletter, May 2012.

I don’t recall exactly when my obsession with the weather started, but I know I was very young. Frightened by thunder and lightning, my parents encouraged me to count to measure the gap between flash and crash to determine whether a storm was approaching or leaving. We watched the birds flying high to see if it would be sunny. We looked at dry pine cones or noted whether the cows were standing or laying down to indicate whether we could expect rain.

Weather lore like this nearly always has some basis in fact and I may explore these in future articles.

My weather obsession grew slowly but surely, culminating in purchasing a fully automated, computer connected weather station just before the turn of the century. Then, nearly seven years ago I started recording the weather data so I could build up a historical record.

Connecting the weather station to the internet was the next logical step. The Potten End weather website has been around quietly in some form or other for quite a few years, but recently time and resource has been found to turn it in to something a little more publicly accessible and informative.

Drought and the Hosepipe Ban
With nearly seven years of data to look at, it’s possible to see how our rainfall has diminished in the last couple of years.

• April 2007 to March 2008: 560mm
• April 2008 to March 2009: 682mm
• April 2009 to March 2010: 669mm
• April 2010 to March 2011: 481mm
• April 2011 to March 2012: 472mm

Those figures show that rainfall dropped by 25% to 30% over the last two 12-month periods.
So it’s clearly not just the water companies’ leaky pipes that are causing the problems.

Potten End Weather on the Internet
Potten End weather is available in many forms on the internet. On the website at www.pottenend.org you can view all of the recent weather measurements. The graphs can show data going back up to 90 days.

The web site is still under development. It will mature, change and improve over the coming months. So keep an eye on it!

You can also subscribe to the Potten End Weather Twitter feed at @pottenend. Weather information is tweeted several times a day.

Please note that if you send twitter messages to @pottenend about local information or events, they can be re-tweeted to all of the Potten End Weather twitter followers.