webspotting 3 - ADDS

First published in the Apr/May 2008 issue of SCOPE, the newsletter of the RASC Toronto Centre. It is recommended you open the link in a separate window and then follow the instructions from this window. Republished here with permission.

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This begins a column wherein I will discuss a web site that I stumbled across or regularly use. I hope you’ll visit it. And maybe it will find its way into your bookmarks or favourites.

Let’s kick it off with a weather-related site (since I’ve been talking this lately). In addition to Environment Canada’s offering and the proximal Clear Sky Clock for my planned viewing location, I now regularly look at ADDS. Geoff Gaherty turned me onto this site.

http://adds.aviationweather.gov/

1. From the Aviation Digital Data Service home page, click the Satellite (sky blue) tab. You should see a map of the United States and a smidgen of the Great White North.

2. In the Image Type section, choose a format.

Visible: Generates a black and white photographic display of the cloud cover. Since it is made using visible light, avoid dusk, dawn, or evening time frames. Infrared (Color): Generates a colourful display of the clouds. Thick bands will be represented by purple and blue tones; wisps as yellow and orange. Clear patches will show as red or dark red. Blue is bad; red is good. Infrared (B/W): Heat signatures of the clouds in black and white. Useful for night-time analyses. Water Vapor: Gives a sense of the water moisture in the air, humidity levels, lake effects, etc.

3. In the Display section, specify whether you want a single snapshot of what’s overhead right now or to set it all in motion.

Latest Image: Generates a static image, 680x680 pixels. Loop-small: Produces an animated image or small motion picture consisting of 9 frames. Each frame is 512x512 pixels. Loop-big: Same as above but at the 680x680 size.

4. Click a region. I choose DTW, between Lakes Michigan and Huron, since Ontario weather generally prevails from the west.

The static image or loop is displayed. Loops will repeat for several minutes.

The loop procedures do not require browser plugs-ins. But you’ll need to have the JavaScript option enabled.

The control panel to the left animated image should be obvious. 

I particularly like the Loop Mode feature. The first button (the default) makes the frames play sequentially, 1 through 9, then the movie restarts from the first frame again. The second button however makes the movie play forwards then backwards. Bouncing or reflecting at each end, somehow, this gives a strong impression as to how the air is moving.

To generate a new display, click the @dds Home (violet) button.  Rinse and repeat.

I hope you find this web site handy. If you’re considering going outside, debating whether you should set up the ‘scope or crack open the remote dome, now you can get a better sense of whether the clouds are going to cooperate.

Watching the web,
Blake Nancarrow