This will show you how stable a tripod isn't when it's windy... So if you're still getting blur on your long exposures maybe this is why.
This wasn't a micky mouse tripod either, this was a very heavy Vanguard Alta 264AT with a roughly 1kg head and 1.5kg camera and lens.
The way to avoid this apart from sheltering the tripod is to remove any camera straps, minimise your height and to hang a rock or sand bag from the hook on the bottom of the tripod.
