Rickmansworth Frost Hollow

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

Long since gone (buildings have changed the katabatic drainage) but I'm curious about the history. 

The most interesting I can find is this from wiki:"
Valley Road in Rickmansworth has a frost hollow. This is caused by the local geography, notably the railway embankment which prevents the natural drainage of cold air from a specific part of the valley. The greatest daily temperature range in England was recorded on 29 August 1936 in Rickmansworth when the temperature climbed from 1.1 °C at dawn to 24.9 °C within 9 hours due to this unusual geographic feature".

Approx location TQ042955

This thought was prompted by the fact that today, 31st August, Altnaharra in the North West Highlands, seems to have gone from 0C at dawn to 20C by late afternoon.

Jack

[Tudor Hughes]

I think the range is larger than that.  lf my memory is correct the temperatures were measured in Fahrenheit and the minimum was 34F and the maximum 85F, equal to 29.4C.  A typo or copying mistake has been made and the figure of 24.9C has become established recently.  Everyone has simply copied it (as too frequently happens on the web) but I am certain it is wrong and the true figure is 29.4C.  In any case the indicated range of 23.8 degC is nothing special for such a location as I have personally recorded more than one occasion when the range has exceeded 22 degC here on the fairly well exposed dip-slope of the North Downs. (Warlingham, Surrey).  Figures like that(34, 85) tend to stick in your head.

Tudor Hughes, Warlingham,. Surrey