NCAR Foothills Lab WebCam Image Artifacts

There are a number of moderately odd phenomena and image artifacts associated with the Foothills Lab WebCam.

Some of these obvious, but here are others:

Camera Hood

A hood over the camera appears as curved arcs in the upper right and left of the images, due to wide-angle lens effect.

Apparent Rotations in Clouds

It's not unusual to see rotations in the clouds when viewed in movie mode. Some of these rotations can be real. Others are impressions caused by the wide-angle lens (clouds on the horizon seem to barely move, while close-in clouds move past the camera very quickly), or by clouds at different heights moving in different directions.

Pulsing of Light Near the Horizon

The camera uses an automatic exposure setting. This seems to be a bit inconsistent, and the weighting of the exposure over the image field may not be optimal for cloud photography. This causes odd changes in image brightness, even to the extent that a given feature may disappear and reappear between frames. Pulsing in image brightness can be particularly bad near the times of sunrise and sunset.


Because of the wide-angle lens, contrails usually appear to be curved.


Pretty obvious when they're in focus. If it looks big and has legs, it's an insect (unless it's a bird!).

Raindrops, Snow and Frost

The rooftop camera is largely unprotected. There's a hood that extends over the lens (visible as arcs in the upper left and right corners of the image), but hydrometeors can still impact the lens. Additionally, sudden temperature changes can produce frost on the lens.

Cloud Shadows

Another pretty obvious effect. Clouds may move over the roof, casting a shadow even when the cloud is not visible in the image.


We're near the airport, with the runway approach right over the building or a little to the north. Aircraft are often seen.