THE WEATHER

Bay of Plenty Beacon, Volume 10, Issue 36, 11 October 1946, Page 7

THE WEATHER

OLD ADAGE DEBUNKED CORNS NO BAROMETER The scientific subject which interests the largest number of people is the weather, and, in consequence, more unscientific nonsense is believed about this subject than about any other, writes John LangdonDavies in the • Daily Mail. People prefer to believe bits of weather lore rather than the evidence of their senses. Thus April this year broke maqy records for warmth, and all over my Surrey common the blackthorn was particularly fine, yet on a warm day a neighbour said: “We shall have it cold so long as the blackthorn is in flower.” Another does not expect the weather to change—though, in fact, it has been. changing every day—until the moon changes. Red-Sky Sign When I was very young my mother told me that a red sky at night was a shepherd’s delight and a red sky in the morning a shepherd’s warning, a fact which I have taken for granted ever since. I have only recently read scientific evidence which shows that, in fact, this happens to be true. We all know that the white light of the sun can be split up into colours if it is passed through a prism. The rainbow is simply sunlight split up by the prismatic effect of water vapours in the sky.

Very fine dust prevents rays of light from continuing on their way straight ahead. It scatters the light in all directions, but it does not scatter all light equally. The part of sunlight which is most affected is the blue light. That is why tobacco smoke looks blue. The blue light passing through it towards your eye is affected by the tiny particles and scatters in all directions, so that you see a blue cloud between you and the source of light.

If you think that tobacco smoke is really blue, and that its colour is something more than a mere effect of light-scattering by particles, you can very easily prove that you are wrong. Take a handkerchief and. blow the smoke through it. The result is a yellow stain; the real colour is yellow. If the atmosphere is dusty, most of the sunlight passing through it is lost-and only the red rays get by. That is •why clouds may look red at sunrise or sunset.

The sun, being low, has more dusty atmosphere between itself and us and loses all except the red component of its light. This only happens if the particles of dust are smaller than a fiftymillion of an inch.

That is why the sun looks red through a smoke fog, although, because water drops are twenty times as large as this, the sun seen through a damp mist looks white. Weather From The West Now, in Britain most of the weather comes from the Atlantic. That is, it travels from west to east. In dry weather the air is dusty, but in bad weather either the air is washed clean by falling rain, or unfallen rain condenses on the dust and forms .drops too big to scatter light. So red sky at night means that the air to the west, from which tomorrow’s weather is coming, is dry and dusty and with no rain clouds to hide the sun. We are right in expecting fine weather. In the same way grey sky in the east at dawn means that bad weather is passing away to the east and gives us a hope of fine weather to follow it.

Red sky at morning simply indicates the presence of nearby cloud illuminated from below and is a far less safe prophecy of what is to come.

Of course, there is nothing certain about red sky at night meaning good weather, because although weather on the whole comes from the west, it is often temporarily blown back from the west and east on its back. When Cats Wash It is quite true that cats wash themselves when it is going to rain, and equally true that they wash themselves when it is going to be fine.

It is not safe to use your corns as a barometer, though a bit of dried seaweed will probably tell you if the room is damp, a fact which you should know without any seaweed.