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Typhoon Nora was the third-most intense tropical cyclone on record. Originating from an area of low pressure over the western Pacific, Nora was first identified as a tropical depression on October 2, 1973. Tracking generally westward, the system gradually intensified, attaining typhoon status the following evening. After turning northwestward, the typhoon underwent a period of rapid intensification, during which its central pressure decreased by 77 mb (hPa; 2.27 inHg) in 24 hours. At the end of this phase, Nora peaked with winds of 295 km/h (185 mph) and a pressure of 877 mb (hPa; 25.91 inHg), making it the most-intense tropical cyclone on record (alongside Typhoon Ida in 1958) at the time; however, this pressure has since been surpassed by two other typhoons. The typhoon subsequently weakened and turned northwestward as it approached the Philippines. After brushing Luzon on October 7, the system passed south of Taiwan and ultimately made landfall in China on October 10. Once onshore, Nora quickly weakened and dissipated the following day. The Philippines and Taiwan sustained the most extensive losses from Typhoon Nora, with 36 people losing their lives collectively. In the former, more than 1 million residents were left homeless as high winds and flooding wrecked homes. Damage in the country reached $2 million (1973 USD). In Taiwan, more than 1,000 homes were destroyed and 8,000 people were left homeless. The typhoon was also responsible for several maritime incidents that killed at least four people. ==Meteorological history== On September 30, a weak surface low developed within the monsoon trough about 195 km (120 mi) south of Yap. Drifting northwestward, the system gradually organized into a tropical depression by October 2. Later that day, aircraft reconnaissance revealed the system to have intensified into a tropical storm, at which time it was assigned the name ''Nora''.〔 The system's movement soon became slow and erratic, with Nora executing a counter-clockwise loop on October 3.〔〔 After completing the loop, it attained typhoon status and acquired a temporary northward trajectory.〔 Due to the cyclone's proximity to the Philippines, the Philippine Atmospheric, Geophysical and Astronomical Services Administration also monitored the storm and assigned it with the local name ''Luming''. Late on October 4, Nora began to undergo a period of rapid intensification.〔 Several aircraft reconnaissance missions were flown by the U.S. Air Force 54th Weather Reconnaissance Squadron into the storm between October 5 and 6, documenting the typhoon's dramatic strengthening. By the evening of October 5, Nora had attained winds in excess of 260 km/h (160 mph), ranking it as a Category 5-equivalent super typhoon on the Saffir–Simpson hurricane scale.〔 A recon mission into the storm at this time revealed concentric eyewalls, measured at and . Initially, the aircraft was unable to penetrate into the core of the eye due to severe turbulence; however, they were successful after a second attempt. Once inside the eye, they discovered an almost cloud-free center with "an amphitheater or bowl-like appearance." Stratocumulus clouds were suppressed to an unusually low altitude of . The core of Nora was exceptionally warm, with temperatures reaching a near-record at the 700 mb level. At 0020 UTC on October 6, a dropsonde released by the reconnaissance team recorded a surface pressure of 877 mb (hPa; 25.91 inHg) just inside the eyewall of the typhoon.〔 At this time, maximum winds were estimated to have peaked at 295 km/h (185 mph).〔 This intensity ranked Nora as the most-intense tropical cyclone on record in the world, alongside Typhoon Ida in 1958. However, in post-storm analysis, it was noted that since the dropsonde did not record a pressure at the storm's center, Nora was likely slightly stronger than indicated.〔 Since then, Nora's intensity has been surpassed by two other storms: Typhoon June in 1975 and Typhoon Tip in 1979. Despite the storm's extreme intensity, it quickly began to weaken as it approached the Philippines on October 6. Within ten hours, the pressure rose to 894 mb (hPa; 26.40 inHg) and later dropped below Category 5 status.〔〔 That morning, Nora turned more northwesterly in response to a weakening in a subtropical ridge and an approaching shortwave trough over China.〔 Steady weakening continued over the following days, with the storm brushing the northeastern tip of Luzon, Philippines, with winds of 175–185 km/h (110–115 mph) on October 7.〔〔 Nora's intensity leveled out around 130 km/h (80 mph) on October 8 as it tracked between the Philippines and Taiwan.〔 After passing within 95 km (60 mi) of Taiwan, Nora turned more northerly before making landfall near Xiamen, Fujian as a minimal typhoon early on October 10. Once onshore, the storm rapidly degenerated into an area of low pressure before dissipating the following day.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Typhoon Nora (1973)」の詳細全文を読む スポンサード リンク
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