I would add that this happens only after the definite article, and only with masculine nouns. Uisge/water/rain is masculine, so "the water/the rain" needs the t- to make "an t-uisge", but for instance aimsir/weather is feminine, so "the weather" is "an aimsir".
(I know that in English you wouldn't say "there's THE rain", but in Gaelic you do, probably to make a difference between "there is rain" and "there is water".)
When you would normally use the definite article an/a' you insert the t- in two situations:
When you do not expect lenition (e.g. masculine noun) and the noun starts with a vowel (as here)
When you do expect lenition (e.g. feminine noun, but we will see other uses later) and the noun starts with an s (an t-sùil 'the eye').
Unfortunately that goes well beyond the current level, but it is the correct answer. May be better just to get used to it as it crops up for now. That is the best way to learn.
Note the t- never capitalizes, so if it were a heading it would be An t-Sùil.
Note for anyone familiar with Irish that there is always a hyphen in Scottish Gaelic, whereas there is no hyphen in Irish unless there is a risk of confusion without it, so an tsúil and An tUisce but an t-usice (I hope I've got that right).
Why is the construction now different from the exercises before? I would have expected something along the lines of Tha i t-uisge a-nis... Can anyone help?
EDIT: Seems i missed the difference between it is and there is. But then, should the correct translation not say There is rain now?
Definitely, but it is more complicated that that. I would accept those sentences in Lowland Scottish English, but not without the article. Even in Standard British English, rain cannot be used without the definite article, or some other word, such as some, in sentences such as 'The rain has arrived/started/finished.' I think the whole sentence structure is very Gaelic, but it is very Scots as well. The 'that's the something + adverb or participle' structure is totally normally in the Central Belt:
That's the train away
That's me finished
That's the post here
The use of on here is a bit odd to my ears, and I guess that it is partly due to on sounding similar to ann.
It's explained in the Tips: https://www.duolingo.com/skill/gd/Weather/tips-and-notes.
Why is this any more important than 'The world is going round'? It is normal and doesn't need commented on. It is generally agreed that the most Gaelic of weather-related phrases is Tha turadh ann 'There is a brief dry spell [now]'. There is no word for a prolonged dry spell as there is no need.
No. "An" in this sentence is the definite article - a word-for-word translation of "tha an t-uisge ann a-nis" would be "is the rain there now". I don't see "i" anywhere in the sentence, but it means "she", or "it" if referring to something with feminine grammatical gender.
I'm just a learner too, but I think that 'uisge' on its own would just mean 'water', whereas with a definite article it changes into 'rain', (at least in this specific weather-related sentence). At least that's how I understand it, based on somebody else's comment in another thread. If I'm wrong, someone please correct me - thank you!
On a side note - I love your Totoro avatar, e.freed :)
Edit: I meant "Spirited Away", not "My neighbour Totoro" of course - also a Studio Ghibli production, but a different story. But I love them both!
Just to confuse everybody even more, I'd like to add that I was taught a different way to say "it is raining" at university: "an t-uisge th'ann". I was told that this literally meant "the water is in it". (Note that my teacher was a speaker of Lewis Gàidhlig). This construction makes sense to me, as an Irish person, because we have a similar construction in our English dialect where we would say "the day that is in it", which sort of means "the kind of day it is".
That word order is perfectly valid in both Gaelic and English, although I would say it was less common in both, unless of course you wished to emphasise the 'now'. But the main reason they do not accept it is simply the labour involved in putting in all the options. They have several options anyway, and allowing arbitrary changes of word order would simply double that. So please just stick to the word order given unless the requirements of either language prevent it.
I have in fact argued with them when the word order in Gaelic was unnatural in English - we don't normally say pepper and salt - but in this case there is nothing wrong with the word order they use.
I would guess that it is because it is quite normal in English to say 'there is frost, lightning etc. but it is not normal to say 'there is the rain now', or even the more literal 'there is the water now' to indicate it is raining. The only time I might possibly say it is when discussing when the expected rain would arrive and you suddenly hear it or see it, but this is a different use of the word there so it would be different in Gaelic
Sin an t-uisge a-nis
There's the rain now
There is a genuine phenomenon that I do not understand, that in difficult curcumstances such as when it is difficult to hear, or when you are not familiar with a given language or dialect, it is quite common to confuse p and t even though most people think they sound completely different under better conditions. All I can say is that as you get more used to Gaelic, the sound in this sentence (click on 'more sentences') will become a clear t. You are not the first person to comment on this question, and I have seen it on others too. If anyone can explain, please do. Until then, you will just have to get used to it. One clue that you could use is that the n would turn to an m before a p, so it could never be an push-ge, but rather am push-ge.
When the sentence was "Tha an t-uisge ann" The translation was "There is rain" We added 'a-nis' and it became "It is raining now" Does the a-nis change the interpretation of the sentence beyond specifying when it's happening, or is this a vagary of how the translations were inputted into duolingo's software? (Which, hey, totally legit y'all.)
No the a-nis does absolutely nothing except to specify when it is happening. But the difference is not just random variation in what was put into Duolingo. At the beginning they tended to go for more word-for-word translations. After complaints they changed to more natural English. I would go for the good English, and if it is not accepted it is because the translation has not been updated, so it is legitimate to report as 'my answer should be accepted'.