Mezzogiorno, la mezza, mezzanotte

The Italian word for mid-day is mezzogiorno, and it can be used in place of le dodici (12 AM); unlike the latter, mezzogiorno does not need an article, and since it is singular, it requires singular verb tenses.
Also fractions of the hour can be referred to mezzogiorno:

è mezzogiorno = it's mid-day
sono le dodici = it's twelve o'clock

partiranno a mezzogiorno e venti = they will leave at twenty (minutes) past twelve
partiranno alle dodici e venti = they will leave at twenty (minutes) past twelve

era mezzogiorno e tre quarti = it was twelve forty-five
erano le dodici e tre quarti = it was twelve forty-five

sarà mezzogiorno meno un quarto = it might be a quarter to twelve
saranno le dodici meno un quarto = it might be a quarter to twelve

As you see, mezzogiorno rejects the definite article, thus requiring simple prepositions, and is singular; le dodici instead needs the article, therefore it requires compound prepositions, and is a plural form.

The specific time 12:30 is commonly referred to as la mezza (the half), but it is only used alone.

è quasi la mezza = it's almost half past twelve
torno da scuola alla mezza = I come back from school at half past twelve

The Italian for midnight is mezzanotte, and it it is often preferred to le dodici (12 PM), since the latter is more often used for 12 AM.
Also either alone or in fractions of the hour.
Also mezzanotte can be used with fractions of the hour; as mezzogiorno, it rejects an article, it needs simple prepositions, and behaves as a singular noun.

è mezzanotte = it's midnight
tornò a mezzanotte e cinque = he/she came back at five (minutes) past midnight
fino a mezzanotte meno un quarto = until a quarter to midnight
da mezzanotte alle due = from midnight to two o'clock

.6   TIME ADVERBS & DURATION FORMS

Before introducing duration forms, it is useful to memorize a few adverbs related to time, some of which have already been used in the previous exercises: try to learn them, little by little, as they occur quite often, both in texts and in common speech.

 

oggi	today
domani	tomorrow
dopodomani	the day after tomorrow
ieri	yesterday
l'altroieri	the day before yesterday (this Italian adverb requires a definite article)
adesso	now
ora	now (remember that, as a noun, ora means hour)
spesso	often
frequentemente	frequently
qualche volta	sometimes (literally: "some time")
talvolta	sometimes
di rado	seldom
raramente	rarely
prima	before
dopo	after
durante	during
sempre	always
mai	never

These adverbs follow the same scheme as adjectives: they may be used either before or after the main subject. Which of the two positions depends on which part of the sentence is more emphasized, since in Italian language the last part of the sentence usually carries more "stress":

uso molto spesso il computer = I use the computer very often (emphasis on the computer)
uso il computer molto spesso = I use the computer very often (emphasis on very often)

di rado lavoro = I seldom work (slight emphasis on work)
lavoro di rado = I seldom work (seldom is more emphasized)

The two adverbs sempre and mai, instead, are used according to a further rule, which will be the subject of a future paragraph. By now, simply memorize their meaning.

 

DURATION FORMS

The simple preposition da (or its compound, depending on whether the subject requires a definite article or not) is used to express the starting time of a duration, thus translating several English forms:

 

the form as of...:

da giovedì = as of thursday
da oggi = as of today
dal 13 maggio = as of May 13th

the form since...:

da giugno del 1958 = since June 1958
dall'altroieri = since the day before yesterday
da mercoledì scorso = since last wednesday
da quel giorno = since that day

the form from..., when followed by to... (see below for the second part of this expression):

dal 1975 al 1980 = from 1975 to 1980
da settembre a ottobre = from September to October
dalle cinque alle nove = from five (o'clock) to nine
da adesso in poi = from now on

The simple preposition a... indicates the end of a time length.
Remember that when a is followed by a vowel (especially another a), it changes to ad.
This preposition translates English to, when introduced by from (same case as above):

da lunedì a domenica = from monday to sunday
dal lunedì alla domenica = from (every) monday to (every) sunday
dalle cinque alle sette = from five (o'clock) to seven
da maggio ad agosto = from May to August (notice ad instead of a, due to agosto)

But, as explained in paragraph 7.5, the same preposition a is also used for stating an hour, as English at:

alle sette e mezza = at half past seven
alle nove meno dieci = at ten to nine
all'una e venti = at twenty past one
a mezzanotte = at midnight

When a time length has no definite origin, and only the finishing time is stated, fino a... is used to express the latter, translating several English forms:

the form until (or till):

fino a sabato = until saturday
fino a domani = until tomorrow
fino alle cinque = until five o'clock

the form up to... (also generally used with numbers, measures, etc.):

fino al 1950 = up to 1950
fino ad ora = up to now (notice ad instead of a, because of ora)
fino al quindici = up to number fifteen
fino a sei metri = up to six metres
fino a qui = up to here

the form through...:

catalogo dei prezzi fino al 31 giugno = price catalogue through June 31st
questa tessera è valida fino al 2001 = this card is valid through 2001

Sometimes, when the deadline is not a given day but a month, a year, etc. (as in the second sample sentence), the adjective tutto = all is added to the form (fino a tutto...), to indicate that the month or year mentioned is included within the period. Therefore, the above-mentioned sentence would often be:
questa tessera è valida fino a tutto il 2001

The English preposition for..., expressing duration, is translated by preposition per...:

per cinque settimane = for five weeks
ho lavorato lì per cinque giorni = I have worked there for five days
l'ingresso è gratis per tutto il 1995 = the entrance is free for the whole (year) 1995

In expressing time length, English always uses for + the duration of the action, but Italian also uses another form: da + the duration of the action.
This is the only tricky bit in translating these forms into Italian, so be sure to focus it well.

lavoro da due anni = I have been working for two years
non vedo Paolo da cinque mesi = I haven't seen Paul for five months
la radio non funziona da due settimane = the radio has not been working for two weeks
piove da due giorni = it has been raining for two days

In Italian, this form is rather different from the previous one, although it might seem similar in English:

ho lavorato per cinque settimane = I have worked for five weeks
this sentence mainly gives stress to the time length of the action, and little importance is given to when the action started;

lavoro da cinque settimane = I have been working for five weeks
the English form gives stress to the fact that the action has taken place habitually for the given time (i.e. "I have worked every day for a time length of five weeks"), while the Italian form carries a meaning of "I have been working every day starting from five weeks ago": this is why preposition da is used, as if to say " from a starting moment, five weeks ago".

So, as a practical rule, preposition per gives a sense of duration in time as any similar English form, while da always has a meaning of "time elapsed from that moment", either referring to the future (translating English from, as of, etc. as explained in an earlier part of this paragraph), or in the past, as in this case, though in English it has to be turned into a different form.

Also notice that when preposition da is used for English since, the Italian tense always refers to the latest moment of the action, as if looking at the action back in time, while the English tense refers to the starting moment of the action, or anyway to an earlier time than its end:

non vedo Paolo dal 1975 = I have not seen Paul since 1975

vedo (present tense) is referred to "now", while have seen (present perfect tense) refers to "1975"

dormo da due ore = I have been sleeping for two hours

dormo (present tense) is referred to "now", while have been refers to "two hours ago"

Also when the action happens in the past, there is a difference between the Italian tense and the English one:

non vedevo Paolo dal 1975 = I had not seen Paul since 1975

vedevo (imperfect tense) is referred to the time of the sentence, while had seen (present perfect tense) refers to an earlier time ("1975")

dormivo da due ore = I had been sleeping for two hours

dormivo is referred to the time of the sentence, while had been refers to an earlier time ("two hours before")