Cycles

A glance at Chart 2 will reveal that some of these trade cycles are very short-lived.

Carnot machines work according to cycles of compression and expansion.

Circadian cycles can be easily appreciated in plants.

Tom cycles to work.

He cycles to school.

No one wished it so, but we are the first species to become a geophysical force, altering Earth's climate, a role previously reserved for tectonics, sun flares, and glacial cycles.

Time and again, human beings have believed that they finally arrived at a period of enlightenment only to repeat, then, cycles of conflict and suffering. Perhaps that's our fate.

She usually cycles to school.

Tom usually cycles to school.

Over the course of about 11 years, our Sun cycles from a relatively quiet state to a peak in intense solar activity called a solar maximum.