Monday, 4 April 2011

A storm's a brewin'

It is our third night here at the summit of Mauna Kea and already the nights are starting to drag by. No matter how important the observations you are making, or how amazing the night time sky or day time views, the slow drag of nightly repetition makes it hard to maintain concentration. This evening, though, our alertness has been raised by the weather. Not, you understand the weather at the summit, and certainly not the rain clouds that always lap against the eastern shores of the Big Island; these weather systems are far below us, looking more like an ocean of cloud from the summit. We are more concerned with the high clouds above us - cirrus.

An image taken from the GOES satellite - taken from the Mauna Kea Weather Center - showing the location of cirrus around the Hawaiian islands.

Cirrus clouds are the bane of an observer's existence, because these high ice clouds can cover over the sky, even when you observe from the top of a mountain as high as Mauna Kea. There's nothing you can do about them, but try and wait them out. Tonight, as you can see in the satellite image, we are riding the edge of a giant mass of cirrus to the south of us. Right now the sky is clear, but we saw our data getting scattered by thin wisps an hour ago. It could easily come back soon. To make matters worse, the even thicker set of cirrus to the north is slowly, day by day, forcing its way towards us and there are rumours of a storm coming. Storms are bad, because they cause hot air to rise much higher than is normal, dragging the water laden clouds with them. If they reach us, then the telescope has to close, in case water starts to condense on the telescope mirror.

So we sit, gripped by satellite imagery, high intensity all-sky cameras and even looking out at the night sky with night-vision goggles, hoping to understand what the weather holds for us.

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