Near-Realtime Cloud Satellite-Imagry
for the
Helena Clear Sky Chart

See the original of this map on NESDIS/NOAA.
Or zoom out to larger map.

How to read it

This is a combination of near-realtime satellite images taken in many different wavelengths. It identifies different cloud types -- even fog. It uses a complex color coding. But the interpretation for astronomy is simple. If it's moving: It's cloudy. It's not not moving: The sky is clear there.

The circle and cross marks the site of the Helena clear sky chart.

How to read the time?

The times on this image are in Zulu time, also known as GMT or UTC. To convert UTC to the local time of the Helena clear sky chart, subtract 6.0 hours.

You're oversimplifying. I want the details.

A full explanation of the color coding, and the types of cloud shown on this image, is here.

How do I control the animation?

The controllable version of this image (without the circle) is here.

Where is it from?

This is the "Day Cloud Phase / Night Microphysics" composite satellite-image by the STAR GOES Imagery Site team. Hosted by NESDIS, the National Environmental Satellite, Data, and Information Service.

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