In these and other ways, it has come about that a pair of red flags with black centers strikes fear into the hearts of seafaring men and terrifies people in towns and cities in the line of advance of the big winds. The warning brings to their minds raging seas and screaming gales, relatives and friends lost in other great storms that have roared out of the tropics, ships going down and buildings being torn apart. Ahead of the storm, the sea becomes angry. Huge rollers break on the beaches with a booming sound. In the distance, a long, low, angry cloud appears on the horizon. If the cloud grows and puts out scud and squalls, spitting rain, the warning flags flutter in the gusts and the big winds will strike the coast with terrible destruction. If the distant cloud is seen to move along the horizon, the tumult of wind and sea on the beaches will subside. The local indications in the sky and the water tell a vital story to the initiated but the warning they give does not come soon enough. It is necessary to know what is going to happen while the hurricane is well out at sea. This depends on the hurricane hunters, and so the messages they send ashore while fighting their way by air into the vortices of these terrible whirlwinds are awaited anxiously by countless people. Tracking and predicting hurricanes is an exciting job, often a dangerous one. But it is not a one-man job; it requires the co-operation of many people. A tropical storm of hurricane force covers such a vast area that all of it cannot be seen by one person. Its products—gales with clouds and rain—and its effects—destruction of life and property and big waves on the sea—are visible to people in different parts of the disturbance. But before we know much about it, the little that is seen by each of many people on islands and ships at sea must be put together, like clues in a murder case. The weather observers who get the clues and the experts who put them together are the hurricane hunters. For at least five hundred years it has been known that these terrible disturbances are born in the heated parts of the oceans. Down near the equator, where hot, moist winds are the rule, something causes vast storms to form and grow in violence, bringing turmoil to the ordinary daily round of gentle breezes and showers. They have come to bear the general name of tropical storms, though known locally as hurricanes, typhoons, or cyclones.