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June CET


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The latest scores are now in,

Three players got it right this month, so well done to The PIT, sufc and Potent Gust

Overall Stargazer leads from Don with RAIN RAIN RAIN in 3rd place, but it remains very close at the top.

:D 3rd!

My complete guesses are still pretty close to the mark!

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Posted
  • Location: South Woodham Ferrers, height 15 metres
  • Location: South Woodham Ferrers, height 15 metres
Corrent me if I'm wrong but in urban area, Asphalt usually absorbe the energy (heat) and reflects the light which would result in much higher temperatures in the Urban area.

Oops, yes you're right. I didn't use the correct scientific language. I meant "radiate" heat!

:D

Perhaps August 1976 being a good example. Warm by night in the city centres but cold out into the countryside as the heat is released slowy in Metropolitans and quicker in Rural areas.

There can be as much as 10c difference between Urban areas and Rural spots.

Good point. And then there is the impact of sea surface temperatures - is the CET area really continental, unaffected by the sea? Rhetorical question.

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Posted
  • Location: Steeton, W Yorks, 270m ASL
  • Location: Steeton, W Yorks, 270m ASL
If there is any urban heat island effects these will be more pronounced when there is greater solar radiation about to heat up, and reflect off surfaces.

I'd imagine a tracker methodology, as I imagined it above, would exacerbate heat island effects.

That might seem logical, but the measured effect is usually greatest overnight in winter under clear skies. UHI isn't only powered by reradiated energy, the energy actually consumed within the urban environment matters too: vehicles, people and particulary buildings and heating. ALL earth surfaces absorb incoming radiant energy to a greater or lesser extent; the man-made component of UHI is much more significant in winter, and then at night.

The integration approach to deriving an average daily temperature would be mathematically more accurate, however, this has only really been practicable in the past few decades when accurate automated readings became possible. The problem in moving to that method of calculation now would be that the long record [of the CET] would be broken. As your example shows, the daily mean would be skewed - upwards in summer, and downwards in winter - compared with the simple arithmetic mean. It is impossible to recreate this retrospectively - far better to be able to continue to compare apples with apples, even though, strictly speaking, this means that the apparent coldest day in the current record may not have been the coldest by all methods of calculating it.

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Posted
  • Location: South Woodham Ferrers, height 15 metres
  • Location: South Woodham Ferrers, height 15 metres

Thanks for that post.

I do recognise how important UHI is in winter, and how noticeable that is compared to the summer when hot is hot, but we should not forget UHI's impact on the maxima over the summer.

In an extreme scenario, the difference in maxima between shaded damp grass away from building under a tree and shade right up against a building on a dry terrace can be 5C.

Likewise, a really hot summer spell heats up walls more than other surfaces and releases this heat at night, which would affect the minima, at a time when the minima is at its shortest anyway.

Given the amount of solar radiation available in the summer, and that UHI is a phenomena of heat radiation, it would not surprise me if in some locations the UHI effect was actually greater in the summer than winter.

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
Given the amount of solar radiation available in the summer, and that UHI is a phenomena of heat radiation, it would not surprise me if in some locations the UHI effect was actually greater in the summer than winter.

That's interesting AF...I think that UHI being radiative is thus solely dependent on temperature difference (Stephan-Boltzmann?) between radiator and radiatee? Which makes me think that wintertime would indeed be favoured. 293 - 253K would be greater than say 310 - 290K for winter and summer respectively? :lol:

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Posted
  • Location: South Woodham Ferrers, height 15 metres
  • Location: South Woodham Ferrers, height 15 metres
That's interesting AF...I think that UHI being radiative is thus solely dependent on temperature difference (Stephan-Boltzmann?) between radiator and radiatee? Which makes me think that wintertime would indeed be favoured. 293 - 253K would be greater than say 310 - 290K for winter and summer respectively? B)

I just thought a brick wall (not an inhabited building, just a wall) in the winter in freezing conditions would be 0C, or just below, day and night.

The sunlight during the day is so milky it's not going to heat that wall up much.

Now, in the summer that wall suddenly gets a lot of heat from the hours and hours of daylight, and it's a radiator.

A weather station cited next to this brick wall must be subject to greater UHI in summer than winter.

Now, a weather station next to an inhibited building, I could imagine the UHI effect being greater in winter because human activity is providing the heat radiation that is heating up the brickwork.

If I don't understand the science, please explain, but I maintain that in some circumstances summer UHI can be greater. B)

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