Charlwood heat Saturday

[jack.h...@gmail.com]

Immediately downwind of Gatwick airport with  its hot tarmac and hot engines.

Jack

[jack.h...@gmail.com]

The Charlwood weather station might be in a dip, so it's naturally hot.  I don't know.

But the frequency with which Charlwood hits the top spot MUST be to do with nearby Gatwick.
Bit of a cheat!  Same for Heathrow.

Jack

[Ashley haworth-roberts]

This is what BBC News posted about Heathrow in July 2022:

Heatwave: Why is Heathrow so hot? - BBC News

[Graham Easterling]

I've seen that before, and I think parts of it a a bit suspect.

He says that there is little difference between Kew & Heathrow. But the graph he shows are average temperatures, not maximum temperatures during a hot spell, which is what we are talking about. That would show a difference. Also to talk about turning on a light bulb in this context, is a bit silly. 

I strongly suspet the position of the Heathrow site is more than a bit iffy.

Graham

Penzance - where it turned very humid and warm again this afternoon. Despite a lot of cloud and a fresh SW wind off the Atlantic, it topped 21C, after a slightly fresher feeling morning.

[Ashley haworth-roberts]

For what this is worth?  Charlwood Location-specific long-term averages 

Do we know the surface wind direction at the time the 33.2 Celsius was recorded (here I think the wind was from a southerly quadrant - but whether more east or more west I don't know (the cloud advanced from the west but that might be a red herring).

In the case of Heathrow (jets, tarmac) and Kew (the gardens are in an urban setting) on 19 June both stations recorded the same high - 32.2 C. (On 20 Liam Dutton tweeted that Heathrow had 30.9 C, narrowly pipping a station in south west Wales with 30.8 C.)

[Graham Easterling]

Ashley, I'm not saying that Heathrow is the warmest place in the UK, or that it always gets the highest temperatures. Getting into individual days is not a good idea, after all Plymouth has been a lot wetter than Bodmin moor recently.

I think the article is really rather poor. The heading is 'why Heathrow so hot'  and says near the beginning "The weather station at Heathrow is located very close to the northern runway, so do the aeroplanes constantly landing and taking off affect the temperatures recorded? Not according to Paul Williams, Professor of Atmospheric Science at the University of Reading"

He doesn't really back this up in any way,  instead he waffles on about sandy soil, the fact it's hotter inland etc. etc etc. which are factors which we all know affect temperature. To mention CO2 emitted from planes and turning on lightbulbs is rather deliberately missing the point big time. What we are talking about here is the emission of huge amounts of hot air (which is rather inviting a smart Alec response!). I think to suggest that jets have no impact on Heathrow temperature readeings is counterintuitive and almost certainly incorrect, and he provides no evidence to contrary.

Every station has it's own individual charcteristics which affect recordings, which he goes on to say, rather arguing against the initial statements. My station in Penzance can be nearly 10C warmer than Camborne (and vica versa) because of the geography of west Cornwall. Braunton Sands used to be quite regularly the hottest spot in SW England in sunny summer conditions. Near the sea but in sand dunes. Walk from the sea, somewhere like Perranporth, into the dunes and it's imediately so much warmer.

I'm not saying Braunton Sands, Heathrow, Camborne or my station etc. are incorrect, but as the writer of the article ends up basically say, every station is unique for a variety of reasons. Heathrow is unique because of tarmac runways a frequent take off of jets, both of which, I believe, must have an impact. It will take a lot to convince me otherwise, even if the answer is Not according to Paul Williams.

Graham

Penzance

 

[jack.h...@gmail.com]

Relevant metars Gatwick

EGKK 211550Z 14007KT 120V180 CAVOK 28/13 Q1016 EGKK 211520Z 14006KT 100V180 CAVOK 28/15 Q1016 EGKK 211450Z 10009KT 9999 -RA FEW035 27/16 Q1016 EGKK 211420Z 14005KT 100V200 CAVOK 27/14 Q1017 EGKK 211350Z 15005KT 120V180 CAVOK 28/13 Q1018 EGKK 211320Z 14006KT 100V180 CAVOK 28/13 Q1018 EGKK 211250Z 17006KT 120V220 CAVOK 29/13 Q1018

So wind 140 + / - degrees.

Jack

[Ashley haworth-roberts]

Noted.

On Heathrow, the tarmac and concrete theory appears to hold some water (well heat anyway) when hot air arrives from the south in summer. I did a short google search on Heathrow summer high peak temperatures (though excluding climate change denialist sites):

Is Heathrow airport really a localised hot spot? - Mayes - 2021 - Weather - Wiley Online Library

The frequency with which Heathrow is the warmest place in the UK is found to peak sharply between June and September.

Evidence of horizontal urban heat advection in London using six years of data from a citizen weather station network - PubMed

We find that London is on average warmer by about 1.0 ∘C-1.5 ∘C than the rest of south-east England... Certain areas, mostly in the centre of London are deprived of urban heat through advection since heat is transferred more to downwind suburban areas. 

Plane theory of Heathrow hot spot doesn’t fly 

Mayes found it was more likely that the built-up environment in and around the airport heats up Heathrow. The weather station there is just 135m north of the northern runway and has only been moved slightly since observations first began in 1946. Heathrow has vastly expanded since then, with large areas of low-rise buildings, tarmac and concrete. That built-up environment is very good at absorbing and then releasing the sun’s energy on summer days, a phenomenon known as the urban heat island effect that keeps cities hotter than surrounding countryside.

Heathrow is a hotspot … but not for the reasons you may think

... west London can be something of a hotspot. But whenever any high temperatures are recorded at Heathrow, there are often rumbles of discontent on social media with criticisms that the airport’s black asphalt runways and buildings absorb and radiate heat, making it particularly hot. But as Tuesday’s joint high temperature showed, there is barely any difference between recordings at Heathrow and Kew, which are only eight miles apart. And yet compared to the hectic pace and built-up environment of Heathrow, the large expanse of greenery at Kew Gardens is something of an oasis, its weather station sited well away from asphalt, concrete and big buildings.