Blue moon on the horizon

Blackberries look tempting
Blackberries look tempting

There’s a curious occurrence this month — August has two full moons.

A full moon appears at the beginning and end of a month every 30 months or so, and when this happens the second one is known as a Blue Moon.

Because the lunar cycle is approximately 29.5 days, the phases of the moon slip gradually out of step with the months. A Blue Moon can never occur in February and is most likely in months with 31 days.

Two full moons in a month have no significance except in folklore, which holds that such a month will be wetter then normal. So we know what to blame for August’s weather. But there is another kind of blue moon, one that really does look blue.

Earth’s atmosphere can split moonlight like a prism, if enough dust particles are floating around. Light from the red end of the spectrum is scattered, while the shorter blue wavelength is intensified, making the moon appear blue.

The moon turned blue over Britain in autumn 1963, thanks to the huge amount of particles thrown up into the atmosphere by a volcano on Bali. When Krakatoa erupted in 1883, blue moons and even blue suns were seen around the world.

Harvest blues

America’s wheat crop has been badly affected by drought this summer, while in Britain the problems have been endless rain and cold winds. Yields are not disastrous, though the quality of some grain is lower than was expected. Only the best is used for bread or breakfast cereals so wheat that doesn’t make the grade has to go for animal feed.

The price of a loaf will rise, no doubt, and so will the cost of other foods. Vegetables such as broccoli and cauliflower have also been affected by the poor growing season. Apple fans will have to pay more, especially for Cox and Braeburn. Some apple trees have produced no fruit at all, because the cold, wet weather in May prevented pollinating insects from flying.

The summer’s rain has made lush growth in our native plants. Shiny blackberries are waiting to be picked in the hedgerows, though in some places the fruit is smaller than usual.

Weather watching

What we need now is a settled autumn. September can be very pleasant, with morning mists giving way to higher daytime temperatures. September 1 gives us hope: “Fair on St Giles Day, fair for the month.”

Maybe that’s too optimistic. The Met Office says that the period from the 1st to the17th is usually “quiet”, unless we catch the tail end of an Atlantic hurricane. If you have a desperate need for a fine day then September 15 is your best bet. Records show that for some reason, it’s almost always a fine day.

Some folk say that weather changes with the turn of the moon. In other words, whatever the conditions when the moon is new or full, that’s how the weather will stay until the moon’s next quarter.

To see if that’s true we’ll have to note the weather at the Blue Moon tomorrow, 
and then see what happens next.