is it autumn or is it winter?

[iapennell]

A proper definition of the seasons and what month falls into what seasons should take account of two or three important factors, the first of which is astronomical. The length of day is shortest over the three months November to January and because the length of day and elevation of the Sun at noon varies like a Sine curve (little change either side of the Solstices, rapid changes near the Spring/Autumn Equinox this would suggest the Winter and Summer seasons ought to consist of four months each and the transition seasons of Spring and Autumn just two months each. The elevation that the Sun reaches (and the length of day) on 26th October and 18th February is exactly (with very small variation from year to year) midway between the elevation the Sun reaches at noon (with exactly 12 hours' day-length) at the Equinoxes of 22nd/23rd September/20th March on the one hand and the low elevation the Sun reaches (with shortest day-length, little over seven hours near Carlisle or Newcastle) at the Winter Solstice on 21st/22nd December on the other hand. By this definition November, December, January and February should be classed as winter months.

The second important factor determining what season a month should fit into is meteorological: The prevailing temperatures, rainfall and sunshine amounts, average incidence of heat in the warmer months and frost/snow near the winter help one decide what season a particular month should go: November is, on average warmer than the three months following it by 2 to 3C and it is also a little warmer than March (has less frost or snow than either these other months), thus it should be defined as an autumn month. However, as with changing daylight levels the average temperature changes a bit more rapidly on the whole in the transition seasons than when it is near the time of lowest average temperature in this country. The average temperature in November is roughly mid-way between the mean annual temperature and the average temperature of the coldest month, in some years warmer and some colder; and with rainfall amounts and light levels on average not far from the mid-winter norms one could justify calling November a winter month (particularly in the north of Britain when the first snowfalls can occur in November). However, also from a metrologist's perspective, it is convenient to classify November as an Autumn month if only to ensure all seasons are equal length and for ease in calculating seasonal and annual temperature, rainfall and sunshine means in a given location: I would thus include November in calculating average temperatures, rainfall and wind-speeds and also (as pointed out above) the official Meteorological definition of Autumn is from 1st September to 30th November (though if you lived in Siberia or northern Canada they might have a different "Official Definition" with October through March being "Winter").

 A third defining factor in deciding what months should be in what seasons ought not only to be average conditions but the POTENTIAL for extremes of heat and cold, weather associated with intense radiative heating or intense radiative cooling SHOULD the right conditions occur: And it is clear November ought to be a winter month based on such definition. Extremes of weather affect communities more than average hum-drum conditions. In November, the day-length is approaching it's minimum- where I live in the North Pennines the day-length is eight hours by mid-month and nearer seven  by the end of the month (by which time the Sun is no more than 13 degrees above the southern horizon at noon) and nights are long. When conditions are right with clear skies and calm for more than a few days hard frosts can occur; freezing fog can form and persist in valleys keeping daytime temperatures there well below freezing; this is especially true if winds over preceding days have come from the Arctic or northern Russia (which are very cold source-regions by mid-November): Persistent hard-frost and freezing fog is severe winter weather by most folks' definitions. Really extreme cold can happen in November if clear dry conditions follow Arctic winds that bring snowfall and establish snow-cover: In Braemar, Scotland a temperature of -23C was recorded in November 1919 (that's just 4C warmer than the all-time record low of -27C recorded in Britain) in just such circumstances; parts of highland Scotland had daytime maxima as low as -10C in late November 1985. It is also possible very cold air to build up over Russia, move west and south under the influence of strong high-pressure over Arctic Scandinavia and meet mild moist air over southern England associated with a depression over northern France to bring widespread disruptive snowfalls- as happened in late November 2010. These sorts of extremes would be regarded as severe, if not dangerous, winter weather.

At the other extreme, strong baroclinicity can (and does sometimes) develop between the already-frigid Greenland/NE Canada and the still mild North Atlantic to bring about the formation of deep depressions with centres below 960 mb that pass over/south of Iceland to bring severe south-westerly gales and torrential rains to much of Britain in November: This brings storm-damage and flooding, whilst removing any remaining leaves off trees- conditions that most would associate with winter .By such reckoning that makes November a winter month.

I can understand folk in the South would consider November an Autumn month, in most years they have to wait until then for their first air-frost and the trees in southern England still have their leaves in full autumn regalia until mid-month but this is certainly not true in Scotland and trees are bare (and garden flowers dead- as a rule) across the whole of Britain by the fourth week of November. If I was asked where to put November as a whole I would say early winter, though I would say that just early November is late autumn and (as a Northerner) would classify early March as late-winter rather than Spring. But for calculating averages I, along with most meteorologists like to keep the seasons equal and would thus lump November with Autumn and March with Spring to keep the calculations simple!      

[Nick B]

This thread had a few chuckles... made me think...

Perhaps a new thread should be opened in the Lounge... something like 'Accidentally Funny'. Classics like IB's WTF moment and OTT rants by others would qualify for nomination... at the end of each month there could be a Nobel Prize-type award where the silliest 1-3 posts would be offered their Netweather place of eternal remembrance in a dedicated thread. The rules being that the poster is quite serious and the comedy value of what they post is unintended but obvious to most. Not sure it's entirely fair or PC but could be amusing...

[Walsall Wood Snow]

I think the reason the solstices are regarded as Mid Summer and Mid Winter is because both Spring and Autumn (and I'm talking about the astronomical definitions of the seasons here) would have once been regarded as sub seasons rather than seasons in their own right. Therefore say after the autumnal equinox it would have been regarded as Winter then until the Vernal equinox when Summer would commence. Obviously half way between them you have the solstices which earned the terms Mid Summer and Mid Winter respectively. Therefore traditionally there were only two seasons with the other two just being descriptive states for the first half of the two main ones which eventually became regarded as separate seasons in their own right. Another thing that has to be remembered that the seasons weren't so much defined by the extreme types of weather we often associate with them, but were invented as time keeping definitions for tracking the annual progression of the Sun. Another name for Autumn of course is Fall, which is a term still widely used in North America and refers to the falling of the Sun from the Autumnal equinox (though actually this process begins after the Summer solstice) to the Winter solstice after which it starts to rise again. 

Of course these days (certainly in meteorological circles, for the purpose of measuring weather conditions in solid tri monthly periods whose beginning always coincide with the 1st of a particular month) the seasons start on 1st Mar=Spring, 1st Jun=Summer, 1st Sep=Autumn and 1st Dec=Winter. This is out of sync though with the traditional definitions but it is defiantly more convenient for recording purposes as it means the seasons begin and end on the same dates every year, with the exception of the end of Winter during leap years when it is one day longer. Though the amount of days for each season isn't equal by the meteorological definition anyway as though both Spring and Summer are equal with 92 days each, Autumn only has 91 days and most Winters that end in a common year only have 90 days, except once every 4 years, in leap years when it has 91 days equalising it with Autumn. That's just a result of the differing number of days in the months they contain though.

Of course the Winter solstice isn't mid Winter by the meteorological definition (that would be somewhere in mid January) or even for that matter the astronomical definition based on the 4 season astronomical year (whereby it's actually considered the start) but by the 2 season astronomical year definition, whereby Spring and Autumn were simply terms for the first half of a 6 month long Summer and Winter respectively (and I believe they once must have been rather than distinct and separate seasons in their own right) you can see why the solstices came to be known as mid Summer and mid Winter.

Edited November 21, 2016 by Walsall Wood Snow

[cheeky_monkey]

According to some on this forum it has been Autumn for the last 3 years..its the only season that exist these days...so its always Autumn.

[iapennell]

13 hours ago, Walsall Wood Snow said:

I think the reason the solstices are regarded as Mid Summer and Mid Winter is because both Spring and Autumn (and I'm talking about the astronomical definitions of the seasons here) would have once been regarded as sub seasons rather than seasons in their own right. Therefore say after the autumnal equinox it would have been regarded as Winter then until the Vernal equinox when Summer would commence. Obviously half way between them you have the solstices which earned the terms Mid Summer and Mid Winter respectively. Therefore traditionally there were only two seasons with the other two just being descriptive states for the first half of the two main ones which eventually became regarded as separate seasons in their own right. Another thing that has to be remembered that the seasons weren't so much defined by the extreme types of weather we often associate with them, but were invented as time keeping definitions for tracking the annual progression of the Sun. Another name for Autumn of course is Fall, which is a term still widely used in North America and refers to the falling of the Sun from the Autumnal equinox (though actually this process begins after the Summer solstice) to the Winter solstice after which it starts to rise again. 

Of course these days (certainly in meteorological circles, for the purpose of measuring weather conditions in solid tri monthly periods whose beginning always coincide with the 1st of a particular month) the seasons start on 1st Mar=Spring, 1st Jun=Summer, 1st Sep=Autumn and 1st Dec=Winter. This is out of sync though with the traditional definitions but it is defiantly more convenient for recording purposes as it means the seasons begin and end on the same dates every year, with the exception of the end of Winter during leap years when it is one day longer. Though the amount of days for each season isn't equal by the meteorological definition anyway as though both Spring and Summer are equal with 92 days each, Autumn only has 91 days and most Winters that end in a common year only have 90 days, except once every 4 years, in leap years when it has 91 days equalising it with Autumn. That's just a result of the differing number of days in the months they contain though.

Of course the Winter solstice isn't mid Winter by the meteorological definition (that would be somewhere in mid January) or even for that matter the astronomical definition based on the 4 season astronomical year (whereby it's actually considered the start) but by the 2 season astronomical year definition, whereby Spring and Autumn were simply terms for the first half of a 6 month long Summer and Winter respectively (and I believe they once must have been rather than distinct and separate seasons in their own right) you can see why the solstices came to be known as mid Summer and mid Winter.

It is also likely that the definition of the seasons that we have, what month falls into which season, is a product of our temperate rainy climate: The warmth of the North Atlantic, it's high specific heat capacity and the prevailing south-westerly winds (particularly autumn and winter) means that the transition seasons of Spring and Autumn are lengthened and all seasons are of the same length. In other locations at the latitude of northern England such as the interior of Manitoba (Canada) or Siberia east of the Urals winters start earlier, are much colder and last later but they have hot summers. I don't know what their seasons would be but they might have something like: December-January (Mid-Winter), February-March (late Winter), April-May (Spring), June-July (Summer), August-September (Autumn) and October-November (Early-Winter); or perhaps the same definitions for Spring, Summer, Autumn but Winter being a six-month season of October through March because their typical weather is with very hard frosts and light snowfalls (with persistent snow-cover) throughout that period of the year. Such a definition would also reflect that there is little lag between insolation levels and temperatures at the surface- temperatures are clearly dropping by mid-August and severe cold sets in by mid-October in most years (such are the features of northern continental climates).

It is certainly the case that the period of cold with bare trees, no flowers, frequent gales and rain (but also the potential for extreme cold given the right conditions) commences in November in Britain- but especially in the North. However, in these globally-warmed times there have been times with markedly above-normal temperatures and warmth in early November (last year being the classic example when 22C was recorded in Wales) and the severe cold-snaps of Novembers' past have become rarer. On that basis it is probably churlish to argue with the official designation of months into seasons as they are, which as mentioned above, is convenient for calculating averages, etc. The seasons as we have them defined divide neatly into four a year, are of the same length and it makes calculating average temperatures, rainfall, wind-speeds for months, seasons and years EASY!

[Essan]

1 hour ago, cheeky_monkey said:

According to some on this forum it has been Autumn for the last 3 years..its the only season that exist these days...so its always Autumn.

I know a song about that  

[titchjuicy]

Autumn

[Walsall Wood Snow]

1 hour ago, iapennell said:

It is also likely that the definition of the seasons that we have, what month falls into which season, is a product of our temperate rainy climate: The warmth of the North Atlantic, it's high specific heat capacity and the prevailing south-westerly winds (particularly autumn and winter) means that the transition seasons of Spring and Autumn are lengthened and all seasons are of the same length. In other locations at the latitude of northern England such as the interior of Manitoba (Canada) or Siberia east of the Urals winters start earlier, are much colder and last later but they have hot summers. I don't know what their seasons would be but they might have something like: December-January (Mid-Winter), February-March (late Winter), April-May (Spring), June-July (Summer), August-September (Autumn) and October-November (Early-Winter); or perhaps the same definitions for Spring, Summer, Autumn but Winter being a six-month season of October through March because their typical weather is with very hard frosts and light snowfalls (with persistent snow-cover) throughout that period of the year. Such a definition would also reflect that there is little lag between insolation levels and temperatures at the surface- temperatures are clearly dropping by mid-August and severe cold sets in by mid-October in most years (such are the features of northern continental climates).

It is certainly the case that the period of cold with bare trees, no flowers, frequent gales and rain (but also the potential for extreme cold given the right conditions) commences in November in Britain- but especially in the North. However, in these globally-warmed times there have been times with markedly above-normal temperatures and warmth in early November (last year being the classic example when 22C was recorded in Wales) and the severe cold-snaps of Novembers' past have become rarer. On that basis it is probably churlish to argue with the official designation of months into seasons as they are, which as mentioned above, is convenient for calculating averages, etc. The seasons as we have them defined divide neatly into four a year, are of the same length and it makes calculating average temperatures, rainfall, wind-speeds for months, seasons and years EASY!

I understand that. My point being however that seasons were originally defined as time keeping concepts for tracking the annual progression of the Sun and had nothing to do with weather measuring purposes. Of course the types of weather we can expect changes from one to the next, but Winter in the original context was a term to describe the half of the year when the Sun is lower in the sky from the Autumnal equinox to the Vernal equinox with the lowest point being at the Winter solstice, which is also refered to as mid Winter. Of course the first half of Winter was and came to be refered to separately as Autumn and as a result it is no longer thought of as being part of Winter anymore. The same applies to Spring and Summer with the latter term once being used to describe the whole of that half of the year, the mid point of course being the Summer solstice hence mid Summer. Of course these four periods came to be regarded as distinct from one another, but they were still terms used for astronomical periods, and many people still track the seasons by their astronomical definitions. Of course meteorologists in time changed the definitions of when they began and ended for their convenience. There's nothing wrong with that but we should recognise their original function was used for measuring the Suns movement in the sky, not weather phenomenon.

[Weather Enthusiast91]

Which ever way you want to look at it (meteorological or astronomical), we are in late autumn. Winter is just around the corner.

[Wynn D Woo]

From a southern based perspective, it is very much Autumn and arguably also the first week or two in December is too most years. Spring tends to start around the third week of February, after that date it takes exceptional weather to get any snow lying more than a handful of hours. March is definitely spring.