Weather InformationWeather InformationWeather charts carry international time/date captions, all referring to the time zone of Greenwich in England, now called Universal Time Constant (UTC), which is the same as the old Greenwich Mean Time (GMT).
To convert weather time and date captions to Australian EST time, add 10 hours; 11 hours during "daylight savings". (Also remember that adding to UTC time can change the date as well.)
On the Bureau's WWW service, there are two types of satellite images; infrared and visible.
Visible images are normal black and white photographs that you would see looking down at the earth - the brightest clouds are usually the thicker ones low down in the atmosphere and the duller clouds are the thin ones such as cirrus.
Infrared (IR) images convert the temperature of the cloud, land or sea to a shade of grey. The warmest points are at the ground and are black. The coolest points are high in the atmosphere (cirrus cloud) and are white. In between are shades of grey which become brighter as the cloud becomes colder (higher). The dull grey cloud which you see on IR images is low to middle cloud.
Sometimes the differences in temperature of the ground can also be seen as different shades of grey.
Some IR photographs are computer enhanced with colour to better show the temperature variations.
The satellite images also have an associated "Z" time. This refers to the nearest UTC hour to which the image is received in full. The image takes about 25 minutes to transmit, starting usually at half past the hour. Thus, the image that is started at 23:32 will be called the 00Z image.
These images are provided courtesy of the Department of Electrical and Computer Engineering, James Cook University, Queensland, which receives and processes the data, and the Japanese Meteorological Agency, which provides the satellite and the raw data.
These are infrared images, enhanced with colour, and calibrated according to the Calibration Chart.
The Satellite Pictures are retrieved from the University of Wollongong's gopher service, which in turn collects them from James Cook University. They are usually updated every 3 hours.
Some gopher and web browsers "cache" items you view (i.e. they keep a local copy of the item) so that the next time you view them they're retrieved from your local computer rather than from the gopher/web service. This means that you're not looking at the latest forecast,
chart, satellite picture etc. To overcome this, use the "Reload" command (available in most browsers), which forces the browser to fetch a new copy of the item from the service.
Understanding Satellite Pictures
Note on Satellite Times ("Z")
About the Satellite Image Service
Warning : Netscape Cache