Monday, June 1, 2015

happy winter

Apparently it's the first day of winter here in Australia. An accident of history: the military used to switch uniforms with the changing seasons at the start of the month, and therefore June 1 (ahead of solstice on the 21st) became known as the official start of winter.

This is a case of two wrongs make a right though. The June solstice is astronomically significant for marking the point in the Earth's journey around the sun when the north pole is pointing most directly at the sun. That is, when the sun is beating down most directly on the northern hemisphere above the tropic of cancer. This (not distance to the sun!) is what causes the seasons. But then you'd think the solstice would mark the peak, i.e. mid-point, of winter, not the first day. That always bugged me as a kid. Summer was obviously May through August*, not late June through late September.

Weather-wise, June 21st still isn't exactly the peak of winter because of the oceans. Water stores a great amount of heat and so stays warm for a long time after heating up in the summer. This effectively keeps the continents warm, especially near the coast, a bit into autumn as well. So the solstice is really just somewhere in the first half of summer/winter.

I.e., June 1 is right about the start of the season. And historical averages confirm that June, July, and August are the coldest months of the year in Brisbane.

And by coldest, I mean that the average daily high temperature is around 75 degrees, with no rain. So, you know, why aren't you all moving here yet :)

*Yeah that's four months, not three. Oklahoma has long summers.

7 comments:

Justin Guinn said...

I agree that seasons should be defined by local weather patterns rather than orbital mechanics. But if you are going to start OK summers at May, then you have to include Sept as well (average highs at the beginning of May and average highs at the end of Sept are both ~76 F). I always used highs > 90 F as my definition of summer, which entails June, July, and Aug. Sorry if this ends up being a double post, my original seemed to disappear into the aether.

JohnRaymond said...

All manner of strange organisms are beginning to breed in your body now that you are no longer experiencing a deep winter freeze ;-) (That's why Minnesota is the most healthful state to live in!)

Vera L. te Velde said...

oh interesting, I remember the start of May being much warmer than that usually :)

Vera L. te Velde said...

hehe or maybe I'm keeping my immune system stronger with constant exposure to non-frozen bacteria...

Justin Guinn said...

Been gone too long I guess!

Anonymous said...

Before I move to Brisbane, how are the summers?

Thanks,

Jim

Vera L. te Velde said...

I enjoy them, but they're not for everyone. They're pretty humid and hover around 80-85 degree highs usually. We had, I think, 2 days up to 100 this year, which is typical, and maybe a week or two cummulatively more in the 90's. But while you have to get used to sweating, there was only one day that was too hot to be outdoors doing fun things when we wanted to, so that's a win in my book :) It's also the wet season but the thunderstorms are brief tropical downpours in the late afternoon, which are exciting and smell amazing, and the rest of the time is sunny.