I'm currently learning the Russian language. While I was in the middle of learning this language and I understood the letters used, I noticed a few cases regarding those letters. One case that got me confused right now is the use of "йа" and "Я". I have seen "Майами" in one article, but it is not spelled "Маями". A similar case goes with "йо" and "Ё". Are there rules regarding those letters?
Yes, both йа and йо are used in russian writing. They are used mostly in loaned words.
Йа (and its counterpart ьа) are used when transcribing foreign proper names only:
Брайан, Гайана, Майами, Яньань
Though I have found a neologism грабьармия which is pronounced as "грабь'армия" without я in the middle of the word.
Йо is used in such nouns as
йог, йод, йота, майор, район, йогурт, майонез.
All of them have foreign origin, though some of them have appeared in Russian vocabulary for many years. For instance, йота is a name of a greek letter and is mentioned in phraseologism "Ни на йоту" which has been used for at least 200 years. Many proper nouns (like Майорка) use йо because of transcription rules (see Stepan Stepanov's answer).
However, sometimes йо can be a result of concatenating two words into one single word. Such words (like самолёт) have a structure word1 + о + word2 (самолёт = сам + о + лёт - "сам летает"). If the first word ends on й, the resulting word will have a йо:
стройотряд = строй + отряд - строительный отряд.
Another interesting case of ё being written in some other way is words like:
бульон, почтальон, каньон, лосьон, сеньор, батальон, медальон, павильон, шампиньон
At first glance it may seem that this is a case when ё after consonant softens the preceding consonant and from йо becomes ьо. But in fact that is not the case. Йо is still there, but is not written. In all these words ьо are pronounced as if it is written as ьйо or ьё: бульйон, почтальйон, etc.
So, as a bottom line, Russian language has no "write as you hear" concept. Though the orthography rules exist, they have many exceptions.
There are plenty of such words; your Майами, or Айова, are examples. However, I am not aware of any words of Slavic origin containing йа or йо; rather, they are loanwords, whether new or old-established. Here, the spelling tends to reflect the spelling of the original as closely as is possible for the different writing systems.
Actually you may see both variants of writing:
Майами - is official name, however, some people may also use
Маями. It's just a problems of transliteration names from one language to another.
There is no special rules about transliteration names.
For example, in common Miami is used to write like
Майами. However, Myanmar is used to write like
Мьянма, with using
If we are talking about common words, like
ёж and so on, there is no difference in the sound of
я. The reason why whe use one or another - is a traditional writing. For foreign words we usually use
йо. For russian words
ё. But it's not a strong rule. You should just remember how to write one or another word. Like in english you will write
photo and not
foto, even if it's sounds the same.
As addition: Russians never use
The sequences йа and йо are used exclusively in loan words. The reason is unknown to me, but for йо I could hypotesize that it is used so to not be confused with е where the dots over ё are omitted. Another idea is that possibly somebody tried to reflect etymology this way.
Personally I would prefer always use я and ё if I could influence the usage.
I think there is no difference in pronunciation. E.g. i pronounce this sound in "Майами" identical to "Маяк". But from other hand i can pronounce Й a bit harder and longer in case of йа.
It is also true, that these combination usually appear in foreign names or geographical names.
I think I've goggled the reason - Англо-русская практическая транскрипция . I don't find ё there. Я is mentioned, but some strange way. So they are not supposed to be used.
But, interesting fact, "Я" and also some strange way "ЙА" are both used for Spanish names Испанско-русская практическая транскрипция
I can suppose, why they avoid to use ё. I don't know why but very often "ё" is written as "e" but still read as "ё". For example nobody will read "Елка" as it looks, everyone understands its "Ёлка" and reads it properly. Probably this confusion makes letter ё to be unwanted in foreign words, because nobody knows how to read it properly in advance.
Be careful, you can find this use
йа, йо, йу in the slang forms!
At the same time all the "right" forms are listed in the ansveres above:
Йод, Нью-Йорк, йогурт, йога, майор, майонез..., it is also may be a "spelled" form of "yo!" -
йоу!, all other forms are slang and they are very popular on the forums and communities:
йож, йад, йа.