You will hear a lecturer discussing the early development of weather forecasting.
You will hear a lecturer discussing the early development of weather forecasting.
First, you have some time to look at questions 31 to 40.
Now listen carefully and answer questions 31 to 40.
In this lecture series on the history of weather prediction, today's talk will concentrate on the earliest stages.
So, let's begin several thousand years ago.
Most ancient societies had gods associated with the weather and disasters such as floods often appeared in stories about the creation of the world.
In general, people explained weather as the result of divine moods.
The variety of weather deities reflects this idea.
The Egyptians, for example, worshipped the sun god Ra, while in Norse tradition Thor controlled thunder and lightning.
Many early civilizations performed rituals, including dances, in the hope that the weather gods would treat them favourably.
Yet weather also affected everyday life.
People had to watch the sky and interpret what they saw correctly.
Their survival could depend on it.
We don't know when systematic observation began, but by about 650 BC the Babylonians were producing short-term forecasts from changes in clouds and other natural signs.
The Chinese also identified recurring patterns.
By 300 BC their astronomers had created a calendar dividing the year into 24 festivals, each linked with a particular weather event.
The Greeks, however, were the first to seek a more scientific explanation.
A particularly important figure was the philosopher and scientist Aristotle, whose thinking remained influential for almost two millennia.
In 340 BC he wrote a work that tried to explain the development of rain, clouds, winds and storms.
He also discussed phenomena in the heavens, including halos, bright rings around the sun, moon or luminous stars, as well as comets.
A surprising number of his observations were correct.
For instance, he understood that heat could turn water into vapour.
On the other hand, Aristotle also reached several false conclusions, among them the claim that the Earth breathed out the winds.
Mistakes of this kind began to be corrected during and after the Renaissance.
Even so, his writings were treated as the main authority on weather for nearly 2,000 years.
During the Middle Ages, observations were also preserved in sayings.
One familiar example is the proverb about a red sky bringing fine weather at night, but warning of poor weather in the morning.
Modern meteorologists have found that many such sayings grew from careful observation and can be reliable.
For centuries, forecasts depended entirely on what individuals could observe for themselves.
In the 15th century though, scientists began to recognise the need for instruments.
Before that, they had little beyond wind vanes used to establish wind direction and simple rain gauges.
An early addition was the hygrometer invented in the 15th century to measure moisture in the air.
It was one of a series of devices that advanced weather forecasting.
Then, in 1592, the Italian scientist and inventor Galileo produced the first thermometer.
Galileo's pupil Torricelli later devised the barometer, making it possible to measure air pressure.
In 1648, the French philosopher Pascal demonstrated that pressure falls as altitude rises.
The English astronomer Halley confirmed this finding in 1686, and he was also the first to chart the trade winds.
As scientists became better able to measure weather-related factors, their understanding of the atmosphere and its processes improved, and observations began to be recorded systematically.
In the 18th century, the scientist and politician Benjamin Franklin investigated electricity, particularly lightning, but weather remained an interest throughout most of his life.
Franklin established that storms generally move from west to east.
Progress in understanding the atmosphere also depended on developments beyond new measuring devices.
Observers in separate places started keeping records, and in the middle of the 19th century, the telegraph allowed their information to be brought together.
By the end of that century, this had led to the first organised weather services.
Mathematics and physics did not become established parts of meteorology until the early 20th century, and that is where we will continue next week.
That is the end of part four.
