When saying the time in Russian do you use cardinal or ordinal numbers and would you use 24 hour clock more than 12 hour?

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“A person who gets out of bed and starts his day very early is called "жаворонок" (= early bird/morning lark). A person who likes to sleep longer is called "сова" (= night owl).

Question: "Is it necessary to specify the time of day when we talk about time?"

Answer: "Most often people say simply: eleven o'clock. If both you and your interlocutor understand the context, then specifying the time of day is not necessary. When you say: "I have breakfast at eleven o'clock", it is clear that you are talking about the morning. But if you want to make an appointment and you say, 'Давай встретимся в девять', it's better to specify, 'Давать встретимся в девять вечера.'"

It is also good to know how the units of measurement of time and the names of the time of day are called in Russian. Some words are consonant with English:

second - секунда
minute - минута
hour - час
quarter - четверть часа
morning - утро
afternoon, daytime - день
midday - полдень
evening - вечер
night - ночь
midnight - полночь
24 hours of a day - сутки»‎

Источник: https://www.ruspeach.com/learning/13480/

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