The direct rays of the sun touch the equator and strike northward toward the Tropic of Cancer. In the Southern hemisphere winter has begun, and it is summer north of the equator. The sea and air grow warmer; the polar air of winter begins its gradual retreat. The northward shift of the sun also brings the season of tropical cyclones to the northern hemisphere, a season that is ending for the Pacific and India Oceans south of the equator. Along our coasts and those of Asia, it is tune to look seaward, to guard against the season's storms. Over the Pacific, the tropical cyclone season is never quite over, but varies in intensity. Every year, conditions east of the Philippines send a score of violent storms howling toward Asia, but it is worst from June through October. Southwest of Mexico, a few Pacific hurricanes will grow during spring and summer, but most will die at sea or perish over the desert or the lower California coast as squalls. Along our Atlantic and Gulf coasts, the hurricane season is from June to November. In an average year, there are fewer than ten tropical cyclones and six of them will develop into hurricanes. These will kill 50 to 100 persons between Texas and Maine and cause property damage of more than $100 million. If the year is worse than average, we will suffer several hundred deaths, and property damage will run to billions of dollars. Tornadoes, floods, and severe storms are in season elsewhere on the continent. Now, to these destructive forces must be added the hazard of the hurricane. From the National Hurricane Center in Miami, a radar fence reaches westward to Texas and northward to New England. It provides a 200-mile look into offshore disturbances. In Maryland, the giant computers of the National Meteorological Center digest the myriad bits of data-atmospheric pressure, temperature, humidity, surface winds, and winds aloft-received from weather stations and ships monitoring the atmospheric setting each hour, every day. Cloud photographs from spacecraft orbiting the earth are received in Maryland and are studied for the telltale spiral on the warming sea. The crew of United States aircraft over the Gulf of Mexico, Caribbean, and Atlantic watch the sky and wait for the storm that will bear a person's name. The machinery of early warning vibrates with new urgency as the season of great storms begins.

单选题 The cyclone season of the Southern hemisphere _____.

单选题 What is true about the storms howling towards Asia?

单选题 When the Pacific hurricanes reach the lower California, most of them will _____.

单选题 What can we learn about the National Hurricane Center in Miami?

单选题 The passage discusses most clearly about_____.