Hi

I thought I would spend a morning looking to see if there was any truth in the old ‘equinoctial gale’ chestnut. I know most people poo-poo the idea that gales are more frequent at periods close to the equinoxes as a popular misconception, but I thought I would try to be a bit more scientific about it, and look at the facts. The only data series that I think could help in this regard was the Lamb-Jenkinson Objective series that is maintained and made freely available by the Climatic Research Unit at the University of East Anglia. It uses a grid of mean sea level pressures across the UK to objectively obtain (amongst other indices) the Lamb Weather classification for each day of the year back to 1871. The units for the ‘Gale Day’ may well be in geostrophic ‘knots’, but I have decided to play safe and just display them as ‘units’ in my chart until someone – maybe one of my readers – can inform me differently. The units don’t really matter greatly anyway as long as the method is the applied across the whole data set.

(see http://xmetman.wordpress.com/ for graph)

As you can see from the results, the chart shows a peak in mid-January that erratically diminishes to around 50% at the beginning of June. This remains fairly flat till the second week of August when it begins to steadily increase up until the beginning of December when it flattens of a little. There is no real sign of any surge in the Gale index at the exact date of either the spring or autumn equinoxes, but there are minor peaks at around the 1st of March, and in the first week of October, that come closest to the dates of the equinoxes.

So no real sign of any equinoctial gales in either spring or autumn, just a steady decrease in the daily frequency of gales in spring, and a steady increase in autumn.

Bruce.

On Wednesday, September 18, 2013 2:17:13 PM UTC+1, exmetman wrote:
Hi



I thought I would spend a morning looking to see if there was any truth in the old ‘equinoctial gale’ chestnut. I know most people poo-poo the idea that gales are more frequent at periods close to the equinoxes as a popular misconception, but I thought I would try to be a bit more scientific about it, and look at the facts. The only data series that I think could help in this regard was the Lamb-Jenkinson Objective series that is maintained and made freely available by the Climatic Research Unit at the University of East Anglia. It uses a grid of mean sea level pressures across the UK to objectively obtain (amongst other indices) the Lamb Weather classification for each day of the year back to 1871. The units for the ‘Gale Day’ may well be in geostrophic ‘knots’, but I have decided to play safe and just display them as ‘units’ in my chart until someone – maybe one of my readers – can inform me differently. The units don’t really matter greatly anyway as long as the method is the applied across the whole data set.

Thank you - interesting stuff.

Anne

On Wednesday, September 18, 2013 2:17:13 PM UTC+1, exmetman wrote:


As you can see from the results, the chart shows a peak in mid-January that erratically diminishes to around 50% at the beginning of June. This remains fairly flat till the second week of August when it begins to steadily increase up until the beginning of December when it flattens of a little. There is no real sign of any surge in the Gale index at the exact date of either the spring or autumn equinoxes, but there are minor peaks at around the 1st of March, and in the first week of October, that come closest to the dates of the equinoxes.



So no real sign of any equinoctial gales in either spring or autumn, just a steady decrease in the daily frequency of gales in spring, and a steady increase in autumn.



Bruce.

CEP Brookes, writing in his 'English Climate' 1954, says of the Autumn equinoctial gales:

'There is often a stormy period in mid-Sept, with a peak date of the 20th. The belief that a violent storm may be expected about the Autumn Equinox goes back at least to Shakespeare's time (Macbeth) and though its origin is not definitely known, it is not improbable that it was brought back by sailors to America, for it happens that West Indian hurricanes are most frequent around that date'

However, Brookes regarded the Spring Equinoctial gales as a complete myth.

Dick Lovett

On Wednesday, 18 September 2013 16:47:48 UTC+1, Dick wrote:
On Wednesday, September 18, 2013 2:17:13 PM UTC+1, exmetman wrote:

As you can see from the results, the chart shows a peak in mid-January that erratically diminishes to around 50% at the beginning of June. This remains fairly flat till the second week of August when it begins to steadily increase up until the beginning of December when it flattens of a little. There is no real sign of any surge in the Gale index at the exact date of either the spring or autumn equinoxes, but there are minor peaks at around the 1st of March, and in the first week of October, that come closest to the dates of the equinoxes.

So no real sign of any equinoctial gales in either spring or autumn, just a steady decrease in the daily frequency of gales in spring, and a steady increase in autumn.

CEP Brookes, writing in his 'English Climate' 1954, says of the Autumn equinoctial gales:

'There is often a stormy period in mid-Sept, with a peak date of the 20th.. The belief that a violent storm may be expected about the Autumn Equinox goes back at least to Shakespeare's time (Macbeth) and though its origin is not definitely known, it is not improbable that it was brought back by sailors to America, for it happens that West Indian hurricanes are most frequent around that date'

However, Brookes regarded the Spring Equinoctial gales as a complete myth..

The median line is more like that in times past a strong gale year would be considered the Equinoctial. Doesn't Brooks or Lamb remark about the solstices too. Winter's in the early 1990 for example?

I read something to that effect on the FAQs recently.

It's quite probable that philosophers of Shakespeare's day may have provided a loose background for a lot of his characters such as for example: Prospero (just going by the choice of his name.)

In more recent times the "equinoctials" have been displaced by super-quakes and recently high VEI eruptions. I don't suppose anyone has made an in depth comparison before dismissing such an idea.

They'd as like to make forecasts by looking through a glass. (Like I did a few years ago, quite successfully IIRC. (Which I do!))

Back to the point: The Intertropical Convergence Zone statistically moves with the tropical storm season. That season as we have seen recently can be as erratic as hell.

The fact the Atlantic season actually starts with the tornado season in the USA seems astonishingly unremarked. However I am pretty sure that the Australian Bureau of Meteorology will provide for us all before it is too late. Of course by then it WILL be too late. (Too late but interesting.)

You've been warned :~)

On Thursday, September 19, 2013 3:30:36 AM UTC+1, Weatherlawyer wrote:

(Like I did a few years ago, quite successfully IIRC. (Which I do!))

They would be the forecasts of earthquakes and volcanic activity, based upon the position of pressure systems, which I monitored and which drove you crazy.

Mainly because of the eight I monitored, only one was possibly (I gave you the benefit of the doubt there) correct. I gave up after that, as it was clear that what you were trying to do was a complete waste of time and monitoring them would be an even bigger waste of time (and still is).

*))