со днём vs. с днём

Question

I'm aware that о is added to some prepositions for historical reasons in some combinations (со дня, ко мне, во сне, etc.). A student recently asked why we usually say с днём рождения instead of со днём рождения and I didn't have an answer.

Quick checks at ruscorpora.ru and Google's Ngram Viewer suggest со днём is used, but much less frequently than с днём; I'm wondering if there's a reason for that.

A question especially for native speakers: do you feel a difference between с днём and со днём?

Answer 1

Preposition со is used: 1)before words which begin with с,з,ш,ж + consonant or with consonant щ

со славой, со звездой, со шкафа, со жгутом, со щами.

2)before the genitive and instrumental case of the following one-syllable words:

лев, лёд, лён, лоб, мох, ров, рот(схватка со львом, виски со льдом)

3) with мной, мною(со мной, со мною)

4)with forms of tbe words

вошь, весь, всякий, всяческий, вторник, второй, второе, многие, многое (со многими людьми, со всяким встречным)

5)with idioms:

со вкусом (to do something ), со вниманием( attentively ), со временем (in the future)--со временем все наладится, со двора (уйти), со дна (достать), со дня на день (soon), со дня (as a point in time for counting)--со дня свадьбы прошел месяц. But : Фотографии с дня рождения.(taken on that very day)

6)with вчерашний we use both с and со

с вчерашнего дня и со вчерашнего дня.

7) Besides, со is used in solemn speech, archaic, humorous,folklore styles, etc.

со товарищи, со Ильей со Муромцем, со крестом

Thus, с днем рождения, фотографии с дня рождения,but:со дня рождения прошло несколько дней.со днем is archaic.

.The sources are reliable :Розенталь and new.gramota.ru.

Answer 2

there is a rule:

1) before many words,started with 2 or more con somatic, especially with „р“, „л“, „н“, "с" (example – со льдом, со шторами, со зла, со всяким, со многими, со мною, со всеми and other.);

2) Before all words started with 2 or more consomatic if first one is "с", "з" (со стыда, со смеху, со страху, со слезами, со ста, со сроками, со своими, со стола, со звездой, со сна, со стариком, со стрелой, со зла, со службы, со слов, со знанием and other.);

3) Before words started with "щ" sound (со щами, со щукой, со щенком, со счастьем и др.)

Answer 3

С/cо днем пришла метель и пурга == (С наступившим днем/вместе с днем) пришла метель и пурга.

Со/c вчерашнего дня, метель и пурга все никак не могли успокоиться.

V.V. pointed some rules out, and it feels like there is slight difference, but if there are some practical reasons (like outside noises, difficulties to pronounce(cold, tongue is frozen and not flexible enough)) to say со дня, со днем - it will be perfectly fine to say in that way.

Although there will be a difference in pronunciation, "со дня" is more fused pronunciation "содня", where "с дня" more separate(not necessary, but kinda tends to).

But when it gets about writing, "o" is just a letter we do not need much in that case.

So answering - "do you feel a difference between с днём and со днём?" - yes, I do, but for me this difference have more practical sense as difficulties of pronunciation and laziness to write in first place. And that "с дня" is more "the day/this particular day as object" and "со дня" is more like period of time, since particular day. Although in most cases(which I come-up at the moment) с/со are interchangeable in usage with word день. (I would like to see example where it is not)
Also "со дня" is more relaxed, "с дня" is more city style.