There is a met picture that I would like to gain access to: the tephigram.
The UKMO does not publish theirs. You need to pay a few grand a year, allegedly, to get access to The Queen's Most Precious data
You can get actual baloon ascent data from Univ of Wyoming, and you can get forecast tephigrams from GFS/NOAA. The details are in this
article. I also have some in the Weather links on my
site.