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xmetman
Sep 7, 2016, 1:22:22 PM9/7/16
to Weather and Climate
I've just heard Nick Miller say that after the passage of the cold front tomorrow it will "feel fresher because of lower humidities".
He's not the first presenter to say that, and I do realise that lower humidities mean lower dewpoints, but I think it will feel fresher tomorrow because of lower dewpoints rather than lower humidities.
I may being a bit pedantic here, but I'm willing to bet that humidities tomorrow won't be that much different from those of this afternoon, and it'll be lower dewpoints that make it feel fresher.
I suppose that you could argue that tomorrow will feel fresher because of lower temperatures AND lower dewpoints because there is an airmass change from tropical continental to tropical maritime.
xmetman
Sep 8, 2016, 11:58:07 AM9/8/16
to Weather and Climate
As promised here are two table of the differences in dewpoint and relative humidity between today at 1400 UTC and yesterday at the same time. I can vouch for the dewpoint being 9.2°C lower at Exeter with the humidity 27.2% lower, and still a very pleasant day with broken cumulus.
The dewpoint at St James Park in London was 7.0°C lower but the relative humidity was just 2.4% lower, at Heathrow the dewpoint was 7.0°C lower and the humidity just 9.3% lower. I still maintain that it was the fall in the dewpoint that made it feel fresher rather than a drop in humidity, but have a look at the figures and make you own mind up.
Dew Point Difference
[A] 14:00 UTC on Wed, 7 Sep 2016 [B] 14:00 UTC on Thu, 8 Sep 2016
In Map Area Lat[49.0 N - 54.8 N] Lon[9.4 W - 2.5 E]
[A] [B] [A-B]
[01] 03844 Exeter Airport 18.3 9.1 -9·2
[02] 03740 RAF Lyneham 17.8 9.1 -8·7
[03] 03710 Liscombe 18.6 10.3 -8·3
[04] 03660 High Wycombe 18.8 10.7 -8·1
[05] 03658 RAF Benson 17.9 9.9 -8·0
[06] 03502 Aberporth 18.0 10.2 -7·8
[07] 03853 Yeovilton 17.9 10.2 -7·7
[08] 03482 RAF Marham 18.4 10.8 -7·6
[09] 03749 Middle Wallop 17.1 9.8 -7·3
[10] 03392 Wainfleet 18.0 10.8 -7·2
03503 Trawsgoed 18.4 11.2 -7·2
[11] 03391 RAF Coningsby 16.6 9.5 -7·1
03746 Boscombe Down 18.3 11.2 -7·1
03628 Filton 18.0 10.9 -7·1
03560 Thurleigh 17.8 10.7 -7·1
[12] 03772 London Heathrow 17.4 10.4 -7·0
03840 Dunkeswell 17.4 10.4 -7·0
03469 RAF Holbeach 17.9 10.9 -7·0
[13] 03529 Pershore 17.4 10.6 -6·8
[14] 03522 Hereford 17.2 10.5 -6·7
03823 Cardinham 18.5 11.8 -6·7
[15] 03971 Mullingar 15.6 9.0 -6·6
03680 Rothamsted 17.7 11.1 -6·6
[16] 03507 Sennybridge 18.4 11.9 -6·5
03808 Camborne 18.6 12.1 -6·5
[17] 03379 RAF Cranwell 16.1 9.7 -6·4
03693 Shoeburyness 17.1 10.7 -6·4
[18] 03488 Weybourne 18.5 12.2 -6·3
03382 Leconfield 17.5 11.2 -6·3
03330 Leek Thorncliffe 16.7 10.4 -6·3
03462 RAF Wittering 17.5 11.2 -6·3
[19] 03351 Rostherne 17.3 11.1 -6·2
03857 Isle Of Portland 18.7 12.5 -6·2
03409 Bala 17.0 10.8 -6·2
03707 RAF Chivenor 18.8 12.6 -6·2
03743 Larkhill 17.2 11.0 -6·2
[20] 03377 RAF Waddington 15.9 9.8 -6·1
[21] 03321 Hawarden 17.2 11.2 -6·0
03649 RAF Brize Norton 16.0 10.0 -6·0
03672 RAF Northolt 16.5 10.5 -6·0
[22] 03970 Claremorris 16.0 10.1 -5·9
03716 St Athan 18.9 13.0 -5·9
03305 Capel Curig 16.6 10.7 -5·9
03770 London St James Park 16.1 10.2 -5·9
03969 Dublin 14.8 8.9 -5·9
[23] 03414 RAF Shawbury 16.5 10.7 -5·8
[24] 03544 Church Lawford 16.7 11.1 -5·6
[25] 03373 RAF Scampton 16.5 11.0 -5·5
03973 Connaught 15.7 10.2 -5·5
03410 Lake Vyrnwy 16.7 11.2 -5·5
[26] 03313 Rhyl 16.8 11.4 -5·4
03535 Coleshill 16.7 11.3 -5·4
[27] 03609 Mumbles 17.9 12.7 -5·2
03978 Finner 14.7 9.5 -5·2
03966 Gurteen 15.7 10.5 -5·2
[28] 03302 RAF Valley 17.7 12.6 -5·1
03385 Donna Nook 16.3 11.2 -5·1
03605 Pembry Sands 17.9 12.8 -5·1
[29] 03354 Nottingham 16.3 11.3 -5·0
03761 RAF Odiham 14.5 9.5 -5·0
03979 Ballyhaise, Cavan 14.9 9.9 -5·0
[30] 03768 Farnborough 14.8 9.9 -4·9
[31] 03604 Milford-Haven 17.7 13.0 -4·7
03961 Oak Park, Carlow 16.3 11.6 -4·7
[32] 03292 Bridlington 16.9 12.3 -4·6
03809 Culdrose 18.1 13.5 -4·6
07020 La Hague 18.3 13.7 -4·6
03344 Bingley 15.9 11.3 -4·6
03647 Little Rissington 16.7 12.1 -4·6
[33] 03316 Crosby 17.3 12.8 -4·5
03827 Plymouth 18.9 14.4 -4·5
03346 Leeds 16.5 12.0 -4·5
03967 Casement 15.7 11.2 -4·5
03862 Bournemouth 16.5 12.0 -4·5
[34] 03917 Belfast 16.1 11.8 -4·3
[35] 03866 St Catherine's Point 18.2 14.1 -4·1
[36] 03911 Lough Sea 15.7 11.7 -4·0
[37] 03901 Thomastown 15.3 11.4 -3·9
[38] 03904 Castlederg 15.9 12.1 -3·8
[39] 03405 Aberdaron 16.7 13.1 -3·6
[40] 07024 Cherbourg 15.6 12.1 -3·5
[41] 03956 Johnstown Castle 16.5 13.1 -3·4
03204 Isle Of Man 16.2 12.8 -3·4
03301 RAF Mona 16.3 12.9 -3·4
03212 Keswick 14.9 11.5 -3·4
[42] 03797 RAF Manston 13.4 10.1 -3·3
03769 Charlwood 14.2 10.9 -3·3
[43] 03266 RAF Linton-On-Ouse 14.9 11.7 -3·2
03781 Kenley 13.1 9.9 -3·2
[44] 03210 St Bees Head 16.9 13.8 -3·1
03962 Shannon 16.5 13.4 -3·1
[45] 03784 Gravesend-Broadness 15.0 12.0 -3·0
03281 Fylingdales 14.6 11.6 -3·0
[46] 07010 Dunkerque 17.5 14.6 -2·9
[47] 03318 Blackpool 16.2 13.4 -2·8
[48] 03803 Scilly 17.5 14.8 -2·7
03872 Thorney Island 15.8 13.1 -2·7
03876 Shoreham-by-Sea 16.8 14.1 -2·7
[49] 03265 Topcliffe 15.2 12.6 -2·6
[50] 03923 Glenanne 15.4 12.9 -2·5
03257 RAF Leeming 14.1 11.6 -2·5
Relative Humidity Difference
[A] 14:00 UTC on Wed, 7 Sep 2016 [B] 14:00 UTC on Thu, 8 Sep 2016
In Map Area Lat[49.0 N - 54.8 N] Lon[9.4 W - 2.5 E]
[A] [B] [A-B]
[01] 03488 Weybourne 93.4 45.6 -47·7
[02] 03292 Bridlington 87.6 52.5 -35·1
[03] 03482 RAF Marham 78.1 43.6 -34·5
[04] 03392 Wainfleet 78.5 46.4 -32·1
[05] 03969 Dublin 86.3 55.3 -31·1
[06] 03560 Thurleigh 79.0 49.9 -29·1
[07] 03844 Exeter Airport 73.9 46.2 -27·8
[08] 03693 Shoeburyness 68.5 43.1 -25·4
[09] 03469 RAF Holbeach 72.1 47.3 -24·9
[10] 03391 RAF Coningsby 66.8 42.3 -24·6
[11] 03710 Liscombe 90.0 65.9 -24·1
[12] 03808 Camborne 89.4 65.5 -23·9
[13] 03658 RAF Benson 73.9 51.5 -22·4
[14] 03522 Hereford 75.6 54.0 -21·6
[15] 03462 RAF Wittering 74.3 52.8 -21·4
[16] 03529 Pershore 73.3 53.0 -20·3
[17] 03660 High Wycombe 80.6 60.4 -20·2
[18] 03857 Isle Of Portland 87.8 68.0 -19·7
[19] 03535 Coleshill 72.8 53.2 -19·6
[20] 03840 Dunkeswell 75.6 56.3 -19·3
[21] 03971 Mullingar 82.2 63.1 -19·0
[22] 03740 RAF Lyneham 71.7 52.9 -18·7
[23] 03967 Casement 83.2 66.1 -17·1
[24] 03382 Leconfield 68.2 51.2 -17·0
[25] 03379 RAF Cranwell 64.7 48.1 -16·6
[26] 03385 Donna Nook 65.5 49.1 -16·5
[27] 03853 Yeovilton 65.9 49.7 -16·1
[28] 03330 Leek Thorncliffe 80.8 65.1 -15·7
[29] 03377 RAF Waddington 62.7 47.2 -15·5
[30] 03544 Church Lawford 69.7 54.5 -15·3
[31] 03749 Middle Wallop 62.3 47.2 -15·0
[32] 03743 Larkhill 69.8 55.1 -14·7
[33] 03680 Rothamsted 70.3 56.2 -14·2
[34] 03373 RAF Scampton 66.4 52.8 -13·6
[35] 03961 Oak Park, Carlow 84.3 70.9 -13·4
03823 Cardinham 83.0 69.7 -13·4
[36] 03649 RAF Brize Norton 64.3 51.2 -13·1
[37] 03628 Filton 70.8 57.9 -12·9
[38] 03716 St Athan 82.1 69.4 -12·6
[39] 03809 Culdrose 85.6 73.1 -12·5
[40] 03351 Rostherne 70.7 58.3 -12·4
[41] 07020 La Hague 83.0 70.9 -12·1
[42] 03966 Gurteen 82.2 70.3 -11·9
[43] 03502 Aberporth 70.8 59.2 -11·7
[44] 03204 Isle Of Man 85.4 73.9 -11·5
[45] 03604 Milford-Haven 82.9 71.7 -11·3
[46] 03970 Claremorris 82.7 72.0 -10·7
[47] 03609 Mumbles 81.0 70.3 -10·7
[48] 03746 Boscombe Down 69.6 59.4 -10·2
[49] 03707 RAF Chivenor 73.6 63.6 -10·0
[50] 03414 RAF Shawbury 68.8 58.9 -9·9
John Hall
Sep 8, 2016, 2:40:28 PM9/8/16
to Weather and Climate
Isn't it actually the lower wet bulb temperature that makes it feel fresher? If we sweat copiously enough, then presumably the sweat evaporating means that it's the web bulb temperature that our skin experiences. Of course, the lower the humidity the greater the depression of the wet bulb temperature relative to the dry bulb..
xmetman
Sep 8, 2016, 3:08:55 PM9/8/16
to Weather and Climate
John
It's a bit chicken and egg I suppose.
Bruce.
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