FAQs on station webcams

Webcam mounted on roof of Green Store at Casey
Webcam mounted on roof of Green Store at Casey (Image: AAD)
Casey Red Shed and site services seen through the webcam Black circle over sun above Casey Red Shed

Why do you have webcams?

The webcams have been installed primarily as an operational device to assist us in our work.

At times, they may be directed towards a particular location, such as a station building, or towards operational activities such as construction work or shipping operations. At the same time, the webcams happen to be useful to record weather pictures, which we publish on our web pages for general interest.

Why are some of the images fuzzy?

Some webcams are mounted on a small metal post, which vibrates in the wind. The camera operates by scanning in lines. When it is windy, in the time taken between scanning lines, the position of the camera has shifted slightly due to vibration. This movement causes a blurring of the image.

Why does a black circle sometimes appear over the centre of the sun?

On occasion, a black circle or other irregular shape may appear in front of the sun in the webcam images. Digital web cameras have image sensors that convert light to an electronic signal. The centre of the sun is very bright, and can overwhelm the sensor. When this happens, the camera software blackens out the area to protect the longevity of the sensor, and displays black pixels in the area.

What is the black or white line that sometimes appears in the photos?

A black line could be one of the guy wires of the tower on which a camera is mounted. In certain light conditions, reflections occur on the dome housing the camera, which can appear as a white line.

How can you tell if the white light in the sky is the moon?

If the light is relatively large and is moving across the sky, it is the moon. Otherwise, it is a fixed object and more often than not, a reflection from one of the station lights.

Do the weather servers accurately record the weather extremes?

At present the 'weather servers' don't necessarily record the most accurate information about weather extremes.

Every five minutes a program runs at AAD Head Office in Kingston that gets the latest image from station webcams, and also asks the 'weather server' on station how windy and cold it is, at the minute the image is retrieved.

The time/date and weather information is stamped on the image and it's published on the internet. If it gets really windy at 2:08 pm one day, for example, then the images at 2:05 pm and 2:10 pm will fail to record this.

This page was last modified on 24 August 2004.