Clouds And Weather, Wind And Weather
Clouds and WeatherGenerally speaking, the higher the clouds, the better the weather is likely to be; the lower the clouds, the worse it is likely to be. In particular, three factors to be taken into account are: movement, change and colour. The following are examples of these. Small cirrus clouds - 'mareâ€™s tailsâ€™ - when they thicken and become lower, are a sign that rain is on the way. Cirro-cumulus - 'mackerel sky' - heralds the approach of rain, and on occasions, of thunder. Cumulus clouds, when they expand early in the day, are also a warning that rain will fall later. Cumulonimbus becomes 'the thunder-cloud' when its top at the front becomes extended so that the whole cloud looks like an anvil. This may be accompanied by a sudden cool breeze, which travels in an opposite direction to that of the actual wind at the time. The cloud and the breeze are signs that a storm is about to break.
Clouds, however, are not only associated with rain and storm. They may also indicate fine
weather. As an example there is the cirrus, previously mentioned, which now appears in a
more promising role. If it does not thicken and seems to be at a standstill or only moving
slowly, in a region of high pressure, then it means fine weather. The 'fair weather
cumulus' is another example. It does not grow bigger, has no marked upward bulges and
moves slowly along. These are the clouds which are often to be seen on a warm summer day.
In the list and the examples given, colour is associated with changes in the weather. It
ranges from the white of cirro-cumulus to the dark grey of nimbo-stratus. The association
is shown in further instances of sky colours, the first of which occurs in the old
Red sky at night, shepherd's delight
Red sky in the morning, shepherd's warning.
It has been estimated that this is true about three times out of five. The second illustration adds another colour to the range: yellow. A watery yellow sunset is a sign of coming rain; a bright yellow sunset is a token of an approaching high wind. Again, a golden ring round the moon is a warning that a storm is on the way. In the last place, there is the rainbow. This multi-coloured arc appears opposite to the sun, and is formed by refraction and reflection of its light through falling raindrops. If the sun is in the east, and the rainbow is in the west and a west wind is blowing, then rain is moving towards the observer. If the sun is in the west and the rainbow is in the east and a west wind is blowing, then rain is moving away from the observer. Clouds then are an index of weather changes; and so is the wind, which we now consider.