There are many reliable weather clues to be found during the day, especially using the clouds.
But it’s worth knowing that there are changes that can be spotted before even the clouds offer any worthwhile insights and one of them is in the night sky and these have been I. Use by indigenous people for years.
Stars twinkle. Their narrow beam of starlight is buffeted and affected by our atmosphere, so it has been on a somewhat crazy ride by the time it gets to us. It is this journey through the air that leads to the twinkling, or ‘scintillating’, to give it its formal name.
Stars near the horizon will twinkle more than those above our heads, because they pass through more of our atmosphere before reaching us. The twinkling also increases when humidity rises, the air pressure drops and there are strong pressure gradients in the atmosphere – all signs of worsening weather.
The easiest way to get a feel for this is during a dry spell. Study the stars of one constellation for a few clear nights in a row until you get a feel for how much they twinkle when things are settled. The fair weather won’t last forever and when you notice your stars twinkling much more than you are used to, rain is on its way.
If the sky is red at night, then there is a good chance that the air to the west of you is clear enough for the sun’s light to have passed through it to reach you and so good weather will follow.
A red sky in the morning can be caused by the dawn light bouncing off high clouds, like cirrus ice crystals in the upper atmosphere. Cirrus clouds can be at the leading edge of a frontal system and so this can also work to indicate the possibility of poor incoming weather.
The mare’s tails are caused by high cirrus clouds that have been shaped by the upper winds. Cirrus clouds can be a signal for an approaching front.
The mackerel scales are cirrocumulus clouds that are being influenced by shifting wind directions and high speeds and are typical of an advancing low pressure system.