Adobe Air is a Shit Sandwich
I don't really need to go much further, the title says it all.
But I will anyway.
I use one Air app at work, the dreaded 'Streamtime' work schedule time sheet monitoring BS. It's so unbelievably slow and bloated I get angry whenever I have to use it in anger.
Seriously, Linux Desktop users will be missing *nothing* but massive headaches, every other day "Adobe Air needs to update itself, Y/N?"
Just firing up an Air application will probably use as much resources as Gnome itself. If you have an electricity usage monitor, you'll see it spike just hovering over the application icon.
It's sad that Met Office are going down this route, but I can bet it's nothing more than their lead developer knows how to create Air apps and is a complete and utter (... insert word of your choice here ...)
As has been pointed out, WTF are they doing? Sure, use Air, but provide a damn XML feed that *anything* can read.
You could claim 1% of users don't matter, but that would be just really really dumb, as you can bet that 1% of Linux users has the most *active* weather geeks you could ever care to meet. I've yet to meet a Linux dev who doesn't have at least a passive interest in the more technical aspects of weather forecasting - it's just in the nature of a tinkerer to lean in that kinda direction.
I'll stop now. I'm getting angry. I may write to my MP. He's also a twat like the lead dev at Met Office. I didn't just say that, did I? Joke. It's all a joke.