Run the provided software demonstrating the use of vector colouring. This is quite a commonly seen technique – the nightly television weather forecast may well use the direction and sizes of its...

Run the provided software demonstrating the use of vector colouring.

This is quite a commonly seen technique – the nightly television weather forecast may well use the direction and sizes of its arrows to indicate wind speed

and heading, with the colours of the arrows also indicating air temperature.

In the example here, two renderings are shown of the same data – the task is

to decide whether the flow is predominantly upwards or down. Try adjusting

the grey of the background on one of the renderings, making it alternately

lighter and darker. What effect do you see and how would you explain it?