Yellow (colour)

Yellow — also known as jaale — is one of the primary colours perceived by the human eye. It appears when visible light has a wavelength of approximately 570 to 590 nanometres. It is the colour associated with the sun, ripe fruit, and gold.

The human eye contains three types of colour-sensitive cells called cones. The perception of yellow arises when the cones responsive to green and red light are stimulated simultaneously and roughly equally. For this reason, on computer and phone screens, yellow is created by mixing green and red light without adding blue.

Technical properties

In the RGB system used on screens, pure yellow is written as red and green at full intensity (#FFFF00). In the CMYK printing system, yellow is one of the four primary colours and is used widely in printing. The difference between the two systems stems from the fact that screens emit light, whereas paper reflects light and absorbs some of it.

Occurrence in nature

In most plants, yellow comes from proteins called carotenoids and xanthophylls. In leaves, when chlorophyll breaks down during autumn, the yellow colours that were already present become visible. In fruits, the yellow colour appears in structures that produce seeds, such as the seed pods.

Public use and safety

Because yellow is easily seen by the eye even in low light, it is used in safety signs, the clothing of road workers, and road markings. In traffic lights, yellow indicates a transition between stop and go. In some sports, a yellow card is a caution issued to players.

Cultural meaning

The meaning of yellow varies across cultures. In many places it is associated with the sun, happiness, and harvest fertility. In some Asian cultures, yellow and gold have been linked to royalty and religion. In other places, it has been associated with illness or cowardice.