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Why Is Britain So Cloudy All The Time?


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Posted
  • Location: Derbyshire Peak District. 290 mts a.s.l.
  • Weather Preferences: Anything extreme
  • Location: Derbyshire Peak District. 290 mts a.s.l.

With regard to New Zealand the prevailing wind direction for much of the country is south westerly, the equivalent of our north westerly, which is a much brighter driection than the moist and cloudy south westerly here.

There will be a multitude of local topographic effects too, which are likely to be more extreme than in this country as the mountain ranges are higher.

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

I've looked quite closely at New Zealand's synoptic progressions recently and my impression is along similar lines to what Terminal Moraine said above. Broadly speaking they appear to spend rather less time in "warm sectors" (almost invariably associated with moist tropical maritime air when they affect the British Isles) and have rather less issues with secondary cyclogenesis, so the end result is that they spend significantly more time in the bright, showery polar maritime airmasses behind cold fronts. It may also help being at lower latitudes and thus spending larger amounts of time under the influence of the irregular succession of anticyclones that move across the mid-latitude Southern Hemisphere than locations at 50-60 degrees S do.

There are indeed topographical effects to take into account although it's worth noting that most lowland parts of western New Zealand, despite being very wet, still tend to have more sunshine than a large majority of the UK.

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

I've looked quite closely at New Zealand's synoptic progressions recently and my impression is along similar lines to what Terminal Moraine said above. Broadly speaking they appear to spend rather less time in "warm sectors" (almost invariably associated with moist tropical maritime air when they affect the British Isles) and have rather less issues with secondary cyclogenesis, so the end result is that they spend significantly more time in the bright, showery polar maritime airmasses behind cold fronts. It may also help being at lower latitudes and thus spending larger amounts of time under the influence of the irregular succession of anticyclones that move across the mid-latitude Southern Hemisphere than locations at 50-60 degrees S do.

There are indeed topographical effects to take into account although it's worth noting that most lowland parts of western New Zealand, despite being very wet, still tend to have more sunshine than a large majority of the UK.

New Zealand is surrounded by much 'cleaner' air sources. I think the prevailing wind is a southwesterly which is a cool airstream for the country as opposed to us and hence it is polar air not tropical air which is brought in on such a wind -more showery but much brighter than our southwesterly which just brings banks of cloud and usually lots of rain and mist to western parts.

You can't compare out weather with New Zealand. We have a unique weather pattern.

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

I think New Zealand's prevailing wind direction is more of a direct westerly rather than a south-westerly, but they do seem to spend a lot more time under the influence of airmasses of south-westerly origin which essentially amounts to the same thing.

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Posted
  • Location: City of Gales, New Zealand, 150m ASL
  • Location: City of Gales, New Zealand, 150m ASL

I think New Zealand's prevailing wind direction is more of a direct westerly rather than a south-westerly, but they do seem to spend a lot more time under the influence of airmasses of south-westerly origin which essentially amounts to the same thing.

Probably you are right, more westerly than southwesterly. WSW probably covers it!

But it's hard to measure because anywhere you look will have local topographic impacts.

For a maritime, mid-latitude country New Zealand is surprisingly sunny. The main reason for this lies in the topography. There are variable weather patterns, and in every pattern somewhere in the country will do pretty well for sunshine. This means that over three decades things even out and you get relatively high sunshine hours. An interesting comparison is New Plymouth vs Napier. Same latitude, but one is on the east coast and the other on the west, yet their sunshine hours are very similar (maybe only 100 hours different).

The sunniest spots though are the NE corners of both islands (Nelson/Marlborough on the SI, Bay of Plenty/ some of Gisborne on the NI) which both can consistently record 2500 hours of sunshine each year. From experience, living in a spot with 2500 hours of sunshine is very different to 1500 hours of sunshine. It's never so sunny that it gets "boring", but being able to bank on ~5 hours of bright sunshine on an average winter day (instead of 1-3 hours) is really significant. I've sat through winter months with frosty mornings, daytime highs of 14C and over 200 hours of sunshine. It's a very pleasant existence!

My experience from living in both countries is that there are fewer "so-so" days in NZ than in the UK. In the UK the relentless weaks of "nothingness" would drag on seemingly without end! Here a small change in wind direction will suddenly flip your location from being exposed to the crap weather to being brilliantly sunny. For Wellington this is S->SW usually. To our south there is no land at all (until Antarctica thousands of km away), but to our SW is the entire South Island with all its mountains so the worst we get from them is mid or high level cloud.

For us, if the flow at 850hPa is W through to SW, the chances of us getting any precipitation of significant cloud is low. It needs something major happening at upper levels to break this rule.

The higher (and conveniently situated) mountains here make a bigger difference than they would in the UK. So today I think the coldest place was Darfield (cold, cloudy miserable 10C) and the warmest place was Hokitika (200km west, sunny and 26C). Between them is a series of ranges getting close to 3000m in height.

The regularly succession of summertime anticyclones (November-April) probably does help us, but it does not guarantee sunshine and in Wellington I would prefer a cyclonic westerly flow to an anticyclonic situation where we end up stuck in 30kt northerlies and cloud all day long trapped beneath the inversion.

We spend plenty of time in moist tropical maritime flows. Far too much time if you ask me. This summer was bad. One evening I went out and it was 22/22 and drizzling. Simply disgusting weather!

Anyway, there is something kind of appealing about Britain's cloudy weather! Sounds crazy I know. But I visited the UK last summer and the whole country (northern France also) seemed to be bathed constantly in a wintry light. This is dramatically different to the intense, bright light we get down here with vibrant colours and very high visibilities. To me it made the country look bleak, but also something like a watercolour painting. I would find it easier to live there than somewhere in Western Australia.

As an aside, apparently the UV index here is 40% higher than at equivalent latitudes in the northern Hemisphere. I don't know how to compare with the UK latitude, but a rough estimate suggest that it could be something like 60-100% higher here than in the UK. So coupled with the raw sunshine hours being higher, the overall exposure to UV here must be way beyond what you would get in the UK.

Edited by J07
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