Sideways Orion

Useful Weather Resources For Observers September 14, 2010

Weather is very important to astronomers. Here are some of my favorite weather-related resources.

The National Oceanic and Atmospheric Administration’s National Weather Service is responsible for issuing forecasts and warnings. In fact, those emergency broadcasts that interrupt your TV show to tell you to take cover come from the NWS.  http://www.weather.gov/

The NWS pages are generally very basic, and their maps can be hard to read if you don’t know what you’re looking at. Most weather outlets use the data from the NWS, and of course post the warnings, but then modify or enhance it in some way. The Weather Underground is one of my favorites.  In particular, their wundermap allows you to select radar or satellite or both, map the severe weather warnings, or just show what your local weather stations are reporting. You can zoom in and out or move around so you can see what’s overhead and what’s coming.  You can also adjust the sensitivity of the satellite or the frequency of the radar. With some practice, you can figure out if the clouds might clear off or if you should just go to bed. You can even track bird and insect migration with the radar! (go to “About Maps and Radar” under resources on the home page.) They also have useful information like sunrise and sunset right on the main forcast page, and a fairly nice star chart.  http://www.wunderground.com/ National wundermap at http://www.wunderground.com/wundermap/?lat=38.54817&lon=-95.80078&zoom=4.

Clouds and precipitation aren’t the only things astronomers worry about.  There’s also transparency and seeing. Transparency is how transparent the atmosphere is.  The more water there is, the less transparent the air is.  On a foggy morning, the transparency is very very bad. Seeing is how shaky the air is.  Looking across a hot parking lot, you can see the air shimmer, looking like wavy water.  That is bad seeing.

The Canadian Meteorological Centre has a forecast for both transparency and seeing. However, like the NWS, they don’t have the most user friendly interface. That’s where the Clear Sky Clock comes in.  It presents the data in a graphical format, though you’ll want to study the key for a bit before you really get the hang of it. Most observatories link to their local clock, but you can find yours at http://cleardarksky.com/csk/.

The Clear Sky Clock is one of the projects at http://cleardarksky.com/. They are also trying to improve their predictions for seeing. If you have a 6″ or larger telescope and know how to tell the difference between turbulence caused by the ground, your telescope tube, and the air, you can help them (and the rest of us.) http://seeing.cleardarksky.com/so/index.html

Ultimatly of course, especially here in Michigan, weather still has an element of chaos. No matter how good the satellite images look, or what the Clear Sky Clock says, you should always look for yourself before opening the dome or carrying your optics outside.