Sunday, 28 February 2010

March - Summer's Last Gasp?



My seasonal correspondent (in that he emails me seasonally, about seasons), Rick Kemp, asked me a few weeks ago whether I thought 1 March was the first day of Autumn.

Rick has thought longer about seasons that me and I'm aways eager to hear his views. As always, he was diplomatic. He knows I favour seasons based on climatic and environmental changes, while he, on balance, prefers what he calls solar seasons (seasons based on distance of the earth from the sun).

I should stress that Rick's solar seasons are not your run-of-the-mill four seasons. He would prefer a series of transition periods between each of our classic seasons, resulting in maybe eight recognisable units. But that's for another day.

The last email, in late February, was all about when autumn starts in Sydney. Rick first presented the case for tradition, at least in Australia, where autumn starts on 1 March.

Our calendars say it's autumn so it must be. April and May are the autumn months. More interestingly, Rick observes some of the 'indicator plants' of autumn are doing there thing. Sasanqua camellias are starting to flower, Freesia leaves are emerging from the soil and autumn crocus are blooming. I noticed myself that Plane Trees leaves are browning at the edges, getting ready for their autumn drop.

Alternatively, using Rick's 'solar seasons', autumn (or the transition season leading to autumn) has already started with the rapid shortening of photoperiod, particularly in the afternoon. Rick feels there is less need of a shoulder season between summer and autumn than there is between winter and spring.

The third alternative, and my preference at the moment, is that summer continues until the end of March and we have a short autumn in Sydney, from April to May. As Rick noted, it still feels like summer. In many Northern Hemisphere countries the Equinox (around 21 March) is used for the start of autumn so in that system there are plenty more weeks of summer left. In Australia, we now finish Daylight Savings on the first Sunday in April so that's a very neat place to finish summer.

I will admit that a week or so ago the mornings began to get a little crisper and the heavy humidity of high summer seemed to have passed, but I'm wary of these temporary weather fluctuations. The heavy rains in early February created a distinctive climatic feel for us in Sydney this year, and who knows what is around the corner in March. Also, are we experiencing a kind of 'shoulder' period similar to early December?

Maybe it doesn't matter, but at the very least I'm observing plants and animals more closely, and I'm judging seasonal changes more by the environment and climate than the cadences of a calendar.

Image: The first sasanqua camellia flowers for 2010 in my own garden. For more on seasons see previous postings.

4 comments:

Jim said...

Bah! Scientists! Always complexifying the simple; always analyzing the hole and not checking out the doughnut. It is a demonstrable fact that here are only two seasons: the 'hot', centred on the summer solstice; and the 'cold' centred on the winter solstice. Plants know this - in one season it is too hot and dry to do anything useful, the other, too cold.

Given this, there must obviously be two transitions, and these surround the autumn and spring equinoxes.

The are no start and end dates, only peaks, troughs and the slopes between. Seasons do not have beginnings and ends; they only have middles. We pagans discovered this millenia ago. We celebrate the middle of the season and the middle of the transition with our ritual slaughter of domestic animals, excessive drink and general debauchery and have long since given up looking for the edges.

In short, the answer to the age old question: there is no hole, there is only doughnut.

Tim Entwisle said...

Well, that may be true in Canberra... Actually it's probably true in the real world as well but we humans do enjoy categorising things - you may be aware of this hobby called taxonomy?

My friend Rick Kemp would probably agree with you more or less (more about the soltice and less about ritual sacrifice I imagine) - he likes the cleaner system of 'solar seasons'. For me, I like the warm fuzzy feeling of tracking the changing world around me.

My friends in Melbourne agree there are only two seasons - footy season and cricket (or to some, not-footy) season.

Tim Entwisle said...

I should add (and correct) that not only as Rick Kemp's 'summer/autumn transition' begun - as I note in my 28 February post - but it has also finished!

Rick identifies an important photoperiod (i.e. length of days relative to nights) change between Australia Day and Valentine's Day, a 19-day transition period between summer and autumn.

And I would note that today's chilly autumn weather in Sydney makes my extended summer seem a little luck warm this year...

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