Question

Radar can work day and night irrespective of the nature of weather. Why?

Answer 1

Once the radar has emitted a microwave signal, the power with which an object reflects the signal is measured. This is called the backscatter. The rougher the sea, the higher the backscatter and the brighter the image (have a look at the green arrows in the figure above, their size indicates the brightness of the image). A calm sea would appear black in the black-and-white image, a windy or stormy sea would be bright, due to the height of the waves. Ships also appear as bright points since they are made of metal and have a lot of right angles that reflect the microwave energy better than water. There are of course other factors involved, as we'll see in some of the other exercises.