Originally Posted by
chaika >long o sounding words that might help: mow, doe, blow, grow, know, glow, etc.
These are not long /o/. They are a sequence of a vowel plus a semiconsonant, which is the /w/ sound. I am not up to date on my phonetic terminology, maybe it's a semivowel, like /j/ which is usually spelled "y".
So you have phonemically (not the spelling!) /mow, dow, blow, grow, now, glow/. Our "long" vowel is really a diphthong, unlike the Russian stressed /o/, which is not. The word сегодня should sound like /s'ivódn'a/ where the /ó/ sounds like the BrE vowel in caught but is short because Russian does not have long vowels (generally). (apostrophe is the standard notation for palatalized consonant).
Оля, спасибо за ссылки на звуки. В некоторых наших диалектах caught звучит как кат, но в моей речи ясно звук "aw" а не [a]. Мой диалект - midwest (вырос под Чикаго).