Ronaldsway WMO 03204 Versus Market Bosworth DCNN 4303. – one is Class 1, the other Class 5 but which one?

Ronaldsway 54.08530 -08530 Installed 1/1/1946

Market Bosworth 52.62321 -1.39548 Installed 1/3/2002 {Image courtesy John Welford – geograph.org.uk – 4619086.jpg}

Figured out which one yet?

There is very clearly something terribly wrong with the Met Office interpretation of CIMO standards if one of the above stations is officially designated as pristine and meets all the very highest standards of Class 1 whilst the other meets no standards at all and is rated Class 5. A reminder of Class 1 standards

Well rather obviously from the headline image of Ronaldsway it must fail Class 1. The area delineated in the 100 metre circle is unquestionably NOT “At more than 100 m from heat sources or reflective surfaces (buildings, concrete surfaces, car parks, etc.).” Whilst the surrounding land is flat, the vegetation is hardly typical but that is fairly irrelevant considering the extent of hard-standing and this is a fully operational airport. It is worth remembering that Class 5 is a one line regulation that reads

” 2.6 Class 5 (additional estimated uncertainty added by siting up to 5 °C)
Site not meeting the requirements of class 4.”

The benefit of similar area demarcation for Market Bosworth is needed to fully assess that site as below.

It is probably also wrong to claim Market Bosworth meets Class 1, though in terms of artificial structures and hard-standing it does meet the standard of less than 10% of the area. It comes down to whether or not the trees are considered problematic as open parkland is otherwise perfectly acceptable as representative of Leicestershire. The headline image of the screen suggests this is an open area and the aerial view does not indicate any heavy immediate shading. The screen is set at 129 metres amsl and Ordnance Survey sheet indicates the 130 metre contour covers the main park area which is flat. Zooming into the 30 metre zone to see if a reliable Class 2 is more appropriate indicates the nearby trees are to the north and less likely to cause shading issues.

It would seem that there may be technicalities to rule out Class 1 but denying Class 2 would surely be nit-picking. I feel most meteorologists would accept readings from this site as good quality.

Returning to considering Ronaldsway, Google historic images expose aircraft in particularly close proximity to the screen – below is one of the very many images with both propellor and jet aircraft in view.

Furthermore it is just possible to pick out the screen from “Streetview” imagery in between the aircraft. The windmast is just to the left of the screen in its enclosure below.

So in conclusion it is reasonably straightforward to judge these two stations on their merits. According to the Met Office latest listing:

RONALDSWAY IS CLASS 1 the best you can get……..and MARKET BOSWORTH IS CLASS 5 JUNK the worst you can get.

To repeat my opening line, “There is very clearly something terribly wrong with the Met Office interpretation of CIMO standards if one of the above stations is officially designated as pristine and meets all the very highest standards of Class 1 whilst the other meets no standards at all and is rated Class 5.”

Which one’s readings would you trust?

Source: https://tallbloke.wordpress.com/2025/03/26/ronaldsway-wmo-03204-versus-market-bosworth-dcnn-4303-one-is-class-1-the-other-class-5-but-which-one/