This picture reflects the theme of the four horsemen of the Apocalypse. In the book of Revelations as each of the first four seals were opened they arose each seated on different coloured horses.
White CONQUEST, RED War, BLACK Famine, PALE Death
Each band in the painting reflects one of these. They are varying size bands due to the fact that these 4 aspects vary in our world.
Conquest White has a swirling effect to show that it is ongoing.
Red WAR has a flame and smoke effect to portray destruction
BLACK Famine has a lined effect in the centre like dead trees to reflect dead crops
PALE Death no pattern as Death is the end of everything.