Ale Czad!

What does it mean? And when can it be used?

Something extraordinary.

What a show! What a spectacle! What an action!

czad is coal smoke or carbon monoxide literally

Often, "Ale.." at the beginning of an expression is frequently of surprise or amazement:

Ale wichura! = What a storm! Man, look at that come down!
Ale niespodzianka! = What a surprise!
Czy pan mówi po angielsku? - Ale oczywiście! = Do you speak English? - Why of course/naturally!
etc...

We say usually:

Ależ oczywiście!

Don't ask why :-) It's just a fixed phrase and the 'ż' is probably a reminder of the 'że' particle that used to be popular years ago.

Cinek

Just like "Ależ tak!" Why it's said?? For the same reasons probably that you sometimes say "Kiedy.." vs. "Kiedyś.." etc... Formal vs. informal. The other reasons might well be phonemic. Polish phonology can be a challenge for non-SlavsLOL

it's not so.
KIEDYŚ - it means: once upon a time; some day; sometime; once; yore; back then
KIEDY - when [When are you coming back?] ; as [I saw him drive by as I was waiting for the bus]

Aha! Interesting. One never stops learning ^^

Thanks that helps. I like the saying and it seems to make people laugh.

I always thought it was Co za niespodzianka? Wrong, or can you say it both ways?

Both ways are OK. "Co za niespodzianka" seems to be older form.

There is other chemistry form:
Ale siara! [What a sulfur!] = What a shame! However formally: siara=beestings, siarka=sulfur.

I myself like the most:
Ale sajgon! [What a Saigon] = What a mess!