Page 16 - Quaker News & Views Nov 25 - Jan 26

Do you look at clouds?

A close friend farmed in the hills of Powys. He would look from his window at the clouds and, accurately,
foretell the weather for the day and, often, for much longer periods of time. Cows and sheep were herded
up or down the many hills as appropriate. He was never wrong.

Weather simply describes what is happening to the air, the mixed conditions of the atmosphere. This includes
temperature, pressure, movement and what the air carries, and this directly influences weather that we
experience. In this country, as we all know, we have mixed weather experience. Climate is the average
weather conditions of a location over a long period of time. This means that different places on Earth have
different climates. The word meteorology, the study of weather, comes from the Greek philosopher Aristotle
who wrote a book in about 340 BCE about natural sciences. The clouds from which precipitation (rain) fell
were called meteoros. A cloud, as we are aware, is a visible mass of water droplets, ice crystals, or a mixture
of both, that is suspended in the air, usually at a considerable height.

The origin of the term ‘cloud’ can be found in the Old English words clud or clod, meaning a hill or a mass of
stone. Around the beginning of the 13th century, the word came to be used as a metaphor for rain clouds,
because of the similarity in appearance between a mass of rock and a cumulus heap cloud.

If we could float upwards for about 50 miles we
would be in the earth’s atmosphere where clouds
develop. If we go on rising we would pass though
three layers of cloud* (low at 1.5 miles), mid (2-4
miles) and high-level (roughly 3-8 miles) which
consist of water; each of those holds three forms
of cloud as seen in the diagram. The common
cloud we see is the fluffy, cauliflower-shaped

Cumulus. Clouds are important aids in weather
forecasting.

Light consists of a range
of colours that we can
see in a rainbow. In a Credit: Center for Science Education
cloud sunlight is
scattered equally, meaning that the sunlight continues to remain white to
our eyes and gives clouds their distinctive white appearance. The tops of clouds have a constant source of
white light, they are always white. If we look out of the window of a plane when above the clouds, the tops
of all the clouds will be a brilliant white. Cloud bases are often grey. When light is scattered in a cloud it
usually is sent back upwards, or out to the sides of the cloud, making the tops and sides of the cloud whiter
than the base. This is more prominent in rain clouds because the cloud droplets are bigger, so less light from
the Sun reaches the bottom of the cloud, giving rain clouds their more menacing appearance.

At sunrise or sunset, clouds can take on a red or orange colour. As you will know, this is because during sunrise
and sunset, the sun is very low in the sky and so light has to travel through more of the atmosphere to our
eyes. More of the blue light is scattered and deflected away, so more red and yellow light reaches the Earth.

I am in awe of rain clouds; thick, dark clouds filled with water droplets that become heavy enough to fall to
the ground as rain. When it's about to rain, clouds darken because the water vapour is clumping together
into raindrops, leaving larger spaces between drops of water. Less light is reflected. Those Cumulonimbus

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