Geoff, I have just released an updated version of a cloud base height PHP script.
Please go to the forum thread
'Now available: AJAX/PHP multilingual website templates' to find out more.
Oh, although the script has been designed to use the data files produced by the 'AJAX-PHP Saratoga templates', it can easily be adapted to only use the Cumulus-produced 'realtime.txt' file - a few parameters will need to be changed.
Further information and/or questions you might have will be answered in the forum thread mentioned (linked) above.