Seasonal Change, and scale limits

[st.patrik]

Originally posted by Saber Cherry:

quote:

---

Originally posted by st.patrik:
Think about really really cold places on earth, where maybe it gets a bit warmer during the summer months, but not significantly so - pretty much its just always cold. Similarly with very hot places - seasonal variation is nowhere near as pronounced as in temperate regions.

Um. Like Antarctica? It is cold there in the summer, but planes can land and people can go outside. In the winter, all travel is ceased, people stay inside their little reseach compound, and virtually all of the scientists leave. The pack-ice forms (ocean water actually freezes). Antarctica in the summer is completely different than in winter... the closer you get to the poles, the greater the seasonal variance is.

This is true in hot places too. There's a city in Siberia that gets up to 90F in the summer and -90F in the winter. And deserts like California's Death Valley are very hot in the summer - usually the hottest place in the US, often over 120F - and cold in the winter. Death Valley's records are 134F in July and 15F in January, while the average daily high and low for those months are 115F and 39F.

So, I hate to say it... but you're absolutely wrong, in this case. Seasonal variation is weak at the equator, which is mostly warm and often humid (I've lived at the equator for a couple years). The main equatorial seasonal variance seems to be rainfall (monsoon or non-monsoon). But places that are very hot or very cold almost universally have extreme seasonal temperature variations.

-Cherry

P.S. Death Valley weather: http://wrgis.wr.usgs.gov/docs/usgsnps/deva/weather.html

---

I was thinking about the poles with cold, yes, and my point was not that there is no difference between summer and winter, but that summer is a warmer blip on an otherwise cold year - i.e. there's not a pronounced difference between autumn and winter, or winter and spring. Now I'll be the first to admit I've never lived inside the arctic circle , so if you, or anyone else for that matter, has any hard info on temperature change between, say october and february, I'm willing to be corrected. However, my impression from what I've heard is that if you get far enough north (or I suppose south) it's mostly just cold.

As far as warm places go, I was thinking primarily equatorial, where, as you point out, the seasonal variation is mainly between dry and rainy season. You're totally right that some places get very hot during part of the year and very cold during other parts. In fact I've personally experienced this, growing up in Ireland (which doesn't vary much in temperature), and at the moment living in midwest USA (where it varies much more!). Maybe IW should introduce a new temperature option, that gives you double points - that of extremes both ways, depending on the season

[st.patrik]

Originally posted by Saber Cherry:
the closer you get to the poles, the greater the seasonal variance is.

I forgot to respond to this: are you sure about this? it seems to me more like somewhere around the tropics of cancer and capricorn is where the most noticeable seasonal variations are.

[Saber Cherry]

At the poles, winter is night and summer is day. Seasons are caused by a difference in the length of day in the winter versus summer due to axial tilt. Poles have 24 hour days in the summer and 0 hour days in the winter, so their seasons are the most extreme... while the equator has daylength differences that are very small (maybe 11:30 in the summer/winter and 12:00 in the spring/fall). Deserts tend to not have plants, rain, or nearby bodies of water to moderate their climate, so they get big swings too - even from day to night. Here's the raw data:

http://www.coolantarctica.com/Antarc...le_mcmurdo.htm

Looks like a 30C (54F) swing in average daily temp from midsummer to midwinter. I'd say that's noticable

As for the difference being larger at the tropics of cancer and capricorn... maybe. The poles get so little sunlight that their highs never get very high, and their lows are limited by things like the freezing point of carbon dioxide and sea ice. So, while the seasons are not as extreme away from the poles (where the day and night are each 6 months long), the fact that there is more sunlight away from them allows greater highs, with similar lows during midwinter... yielding greater temperature variance potential.

[ October 22, 2003, 01:25: Message edited by: Saber Cherry ]

[st.patrik]

Originally posted by Saber Cherry:
At the poles, winter is night and summer is day. Seasons are caused by a difference in the length of day in the winter versus summer due to axial tilt. Poles have 24 hour days in the summer and 0 hour days in the winter, so their seasons are the most extreme... while the equator has daylength differences that are very small (maybe 11:30 in the summer/winter and 12:00 in the spring/fall). Deserts tend to not have plants, rain, or nearby bodies of water to moderate their climate, so they get big swings too - even from day to night. Here's the raw data:

http://www.coolantarctica.com/Antarc...le_mcmurdo.htm

Looks like a 30C (54F) swing in average daily temp from midsummer to midwinter. I'd say that's noticable

As for the difference being larger at the tropics of cancer and capricorn... maybe. The poles get so little sunlight that their highs never get very high, and their lows are limited by things like the freezing point of carbon dioxide and sea ice. So, while the seasons are not as extreme away from the poles (where the day and night are each 6 months long), the fact that there is more sunlight away from them allows greater highs, with similar lows during midwinter... yielding greater temperature variance potential.

I read the website - interesting info - I didn't know that they had 3 outPosts down there. Anyways, a 30°C difference is quite a difference, but that's less than Ireland, which varies typically from -10°C to 25°C from winter to summer. And it's a lot less than Ohio, which varies typically from -20°C to 35°C.

Nonetheless your point is taken - there are seasons at the poles.

[ October 22, 2003, 02:58: Message edited by: st.patrik ]

[Psitticine]

I'm no climatologist, but one thing I know is that many other factors play into climatic effects and seasonal shift.

For example, the warm Gulf Stream flows past Ireland and keeps it warmer than it would be otherwise. On the other hand, the jet stream flowing over the Northern US sometimes pulls down colder air from further north when it goes in the right pattern (AKA the "Siberian Express") and cools down those areas quite a bit.

Just a hopefully interesting side-note . . .

[Saber Cherry]

Originally posted by Psitticine:
I'm no climatologist, but one thing I know is that many other factors play into climatic effects and seasonal shift.

For example, the warm Gulf Stream flows past Ireland and keeps it warmer than it would be otherwise. On the other hand, the jet stream flowing over the Northern US sometimes pulls down colder air from further north when it goes in the right pattern (AKA the "Siberian Express") and cools down those areas quite a bit.

Just a hopefully interesting side-note . . .

Wow!!! So you're implying that upper-level air currents are modeled in Dominions II?