The word 'seeing' in astronomical terms has nothing to
do with a star's brightness, but refers to definition.
The apparent brightness of a star is a measure of transparency,
and is entirely different from seeing, though often confused
with it. If you want to take a detailed look at the planets
or our Moon you need to pick a night with good ‘seeing’. Leaving
aside telescopic faults, it may be said that the majority
of poor definition is due to atmospheric disturbances.
The best time to get detailed views of the planets is when
the atmosphere is steady from ground level up through the
jet stream. Low or high level winds cause turbulence and
the mixing of cold and warm air leads to blurring of the
The chart shows the wind at 15000 feet over Europe. It covers the next 10 days weather in 24 hourly
increments. Ideally low wind speed is what you are looking
for. This usually occurs under high pressure. Look for days
when the UK is free of isobars.