How do farm irrigation systems work?

No trip to the Midwest is complete without seeing a lot of farm fields. In those fields, of course, are irrigation systems. Although these irrigation systems appear to be fairly simple, they are actually quite advanced. One of the most pervasive irrigation systems is the center pivot system. At the pivot of this system is a source of water, which spreads to each individual segment. Rotation around the center pivot point is granted by individual electric motors found on each set of wheels. The outermost set of wheels controls the speed of revolution of the whole system. Typically, the outer wheels move at a faster rate than the inner wheels so as to maintain segment alignment, and various angle sensors report to a computer to coordinate wheel speeds. The individual nozzles found on each segment vary in size (and therefore water emission) in order to achieve application uniformity—the closer to the center, the smaller the nozzle size.