Sky's the limit for climate observers

PUBLISHED : Wednesday, 25 May, 2005, 12:00am
UPDATED : Wednesday, 25 May, 2005, 12:00am

USUALLY WHEN weather forecasters say, 'It will be cloudy today', we only have a basic idea of what the conditions will be like.

But more than 2,100 students from 300 secondary schools will know exactly what that means after taking part in a project which will help them understand the weather forecasting system.

'Weather Diary 2005' is jointly organised by the Hong Kong Observatory (HKO) and Hong Kong Education City.

From now until June 17, the students will watch the sky and record the information on the Weather Diary website ( weatherdiary2005) every day after school.

They will jot down their observations as sunny, cloudy or overcast, and if there's a drizzle, shower or heavy rain.

It might sound like a simple task, but a senior scientific officer from the HKO said that the students had to learn some skills.

The HKO conducted a series of talks for the participants last month to give them a better understanding of the principles involved.

The information is also posted on the Weather Diary website.

Participants were told to imagine the sky as a big circle and divide it into eight equal parts.

If the clouds cover about six to seven parts of the circle, it's considered a cloudy day. If the circle is almost filled with clouds, it's overcast.

Wong Tsz-kan, 19, a Form Six student at Ning Po No 2 College, said the programme taught her practical aspects of geography that she could not have learned from textbooks.

'I learned about the different kinds of clouds and how they're formed,' said

Tsz-kan. 'In summer, we often see what is called the cumulonimbus, which looks like a piece of cotton wool, while in winter it's the stratus, which is much flatter and thinner. This is because it's is hotter in summer so more water is vaporised into the air, which leads to the formation of clouds.'

After the month-long observation, the HKO will compile the information collected by the students to study different weather patterns in Hong Kong.