How does China set the time of year?

JA Barnwell, commenting on the Chinese new year celebrations in Dublin (Letters, February 22), says we might model ourselves more on the Chinese who view their ancestors with real respect.

The Chinese year is based on lunar months but tied to the solar year, which explains why its date varies but always is around this time of the year.

Twelve lunar months have about 355 days, which is 10-11 days shorter than a solar year. This is why Muslim months like Ramadan move backwards in the civil calendar. The way this is avoided is by adding an extra month from time to time.