The first "book" Tsering Dondrup read as a child was a Tibetan calendar his parents used to consult for weather information and ideal dates for ploughing and harvesting.

"We had a new booklet every year. The colors of the covers varied, but there was always a delicate painting of cattle ploughing the fields in early spring," remembers Tsering Dondrup, a Lhasa resident whose hair has now turned gray.

As he aged, he learned that years in the Tibetan calendar were identified with different colors including white, black, green, yellow and red. "Yellow stands for the year of the earth, while blue, green and red stand for water, wood and fire respectively," he says.

The year 2012, for example, is the "Year of the Water Dragon," so the corresponding calendar has a blue cover.

But the cattle ploughing scenes hold much greater significance than that, he says of the calendars, which bear a fascinating history and continuing practical application that is often overlooked among more prominent elements of Chinese culture.

"The colors and postures of the cattle's head, horns, mouth, hooves and tail tell the weather conditions of different periods of the year and help farmers decide the time for ploughing and harvest," Tsering Dondrup explains.

When the cattle's head is painted green, it often forecasts heavy wind in spring. Yellow legs indicate a good harvest in valleys, whereas a blue belly suggests ample rain and potential flooding.

The herder on the cattle's back can be a child, a middle-aged or elderly man.

"The herder on this year's calendar, for example, is a boy," Tsering Dondrup says. "This shows the year is auspicious for children but could be ominous for adults."

The boy's green Tibetan robe and white waistbelt are a sign of economic downturn, points out the calendar enthusiast.

A typical Tibetan calendar often has an overview of the year's climate, astrological phenomena and potential calamities, as well as a more detailed list of dos and don'ts for each day and month, according to Tsetop, deputy head of the institute of astrology and calendar calculation, a research body of the Lhasa-based Hospital of Tibetan Medicine.

"It provides an important timeline for Tibetans to figure out when to grow crops and harvest and what diseases may attack at different times of the year," he says.

Many people also consult the calendar to choose auspicious dates for important events such as marriages, inauguration of new homes or funerals, Tsetop also noting that "elderly people like to hang all the used calendars at home as a mascot to ward off evil."

The compilation of the Tibetan calendar was a presentation of astrological research and calculations, says Kunga Rigzin, one of the institute's top researchers.

At 71, Kunga Rigzin has been working on calendar calculations for six decades.

Tibetan calendar calculations, a 2,000-year-old discipline, figure out weather conditions on the basis of planetary movements, using the 12 zodiac houses and the five planets of Mars, Mercury, Jupiter, Venus and Saturn.

"The calendar is derived from the Indian calendar tradition, but has taken in elements from China's interior regions, too, such as the five elements of water, wood, fire, earth and metal," Kunga Rigzin says.

At many times in history, he and his predecessors have given precise forecasts of solar and lunar eclipses, blizzards and earthquakes and their calculations have been praised as "authoritative" by the Chinese Academy of Social Sciences.

Kunga Rigzin and his colleagues are invited to Tibet's regional meteorological station every March and September for medium and long-term weather forecasts.

Weather reports based on their astrological calculations have been broadcast by Tibet TV on a daily basis since 1993. "The program is very popular among viewers, who rely on these reports to arrange travel and agricultural production," reports Liao Jian, head of the Tibet Meteorological Station's video department.

Astrological calculations began on the Tibet plateau around the second century B.C., and the first Tibetan calendar is thought to have been produced in 1206.

Tibetan calendars have 12 months in a year and every 60 years make a full cycle.

Today, more than 300,000 copies of the Tibetan calendar are printed every year. The booklets, popular in Tibet and other Tibetan communities in Sichuan, Qinghai, Gansu and Yunnan provinces, are also sold to Bhutan and Nepal.