Key for Observing Forecast

The following symbology is used in our observing forecast, which is provided courtesy of the people at APanel/7Timer.

Icon Technical Definition
Octet-gram of cloud cover
Blue is for clear while white is for cloud. e.g. the “cake” on the left is 0% cloud while the one on the right is 100% cloud.
Astronomical seeing
From left to right: <0.5″, 0.5″-0.75″, 0.75″-1″, 1″-1.25″, 1.25″-1.5″, 1.5″-2″, 2″-2.5″, >2.5″. In short, the smaller/bluer, the better the seeing condition is.
Atmospheric transparency
From left to right: <0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.85, 0.85-1, >1 (unit: mag per air mass). In short, the fewer bars/bluer, the better the transparency is.
Chances of rain/snow
Atmospheric instability
From left to right: lifted index between 0 to -3, -3 to -5, and below -5.
Humid weather warning
From left to right: relative humidity between 80%-90%, 90%-95%, and over 95%.
Windy weather warning
From left to right: sustained wind speed between 8.0-10.8m/s (fresh), 10.8-17.2m/s (strong), and over 17.2m/s (gale or above).

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