How is the area kept equal in cylindrical equal area projection?
In cylindrical equal area projection, the area is kept equal by projecting the surface of the globe with parallel rays on a cylinder touching it at the equator. This method is also known as Lambert's projection.
The equality of area is maintained at the cost of distortion in shape. While the areas of various parts of the earth are represented correctly, the shape gets highly distorted, especially at higher latitudes. The pole is shown with a parallel equal to the equator, which contributes to maintaining area equality despite shape distortion.
Explanation
The textbook context clearly states that the cylindrical equal area projection is 'derived by projecting the surface of the globe with parallel rays on a cylinder touching it at the equator.' It also mentions under Limitations that 'Equality of area is maintained at the cost of distortion in shape.' The key mechanism is the use of parallel rays for projection, and the trade-off between area accuracy and shape distortion is fundamental to understanding this projection type.