It is shown that in summer an easterly jet stream overlies southern Asia in the high troposphere with core near 15°N. This current is quasi‐geostrophic. Below the level of strongest winds temperatures decrease from right to left across the current looking downstream; above the level of strongest wind (150–100 mb) the reverse is true. Distribution of cloudiness and precipitation in the lower monsoon correspond to that noted in association with westerly jet streams in the temperate zone: precipitation downstream from the region with the highest winds to left of the axis, upstream to the right. The foregoing holds on individual days and climatically during the monsoon season as a whole. Since an easterly jet stream is observed only over southern Asia (and Africa), but not over the Pacific and Atlantic oceans, it is suggested that the current originates in connection with the large‐scale arrangement of land masses and oceans, and with the elevated heat source of the Tibetan plateau.

It is shown that in summer an easterly jet stream overlies southern Asia in the high troposphere with core near I$"'.This current is quasi-geostrophic. Below the level of strongest winds temperatures decrease from right to left across the current looking downstream; above the level of strongest wind (150-100 mb) the reverse is true. Distribution of cloudiness and precipitation in the lower monsoon correspond to that noted in association with westerly jet streams in the temperate zone: precipitation downstream from the region with the highest winds to left of the axis, upstream to the right.The foregoing holds on individual days and climatically during the monsoon season as a whole. Since an easterly jet stream is observed only over southern Asia (and Africa), but not over the Pacific and Atlantic oceans, it is suggested that the current originates in connection with the large-scale arrangement of land masses and oceans, and with the elevated heat source of the Tibetan plateau.

A synoptic study c 8 number of hurricanes at the time of landfall is described with particular re._rence t o the thermal and wind structure in the upper troposphere and lower stratosphere. It is shown that the low pressure core of the mature hurricane, before recurvature, extends not only throughout the troposphere but sometimes protrudes into the lower stratosphere up to about 27 km., the upper limit of this investigation. The upper core is found to be cold above 15 km. with temperatures occasionally 8"-10" C. below normal at the tropopause level. A peripheral ridge and a peripheral jet in the upper troposphere are dcscribed, and the possible role of thesc features, as well as of the cold core, in the hurricane mechanism is discussed. It is suggested that the cold core may be caused by forced ascent above the well-known warm core of the hurricane. It is also shown that a hurricane which has recurved and becomc embedded in the extratropical westerlies may not have an upper cold core and its structure closely corresponds to the classical model. Tentative schematic models of the distribution of temperature and height anomalies are indicated in the case of a mature hurricane before recurvature. A photographic mission into the eye of typhoon Ida in September 1958 by a U-2 aircraft revealed the spectacular features of the cloud structure in hurricanes up to a level of 65,000 ft. (19.8 km.) which were discussed by Fletcher, Smith, and Bundgaard [2]. A research probe into hurricane Ginny up to 21 km. was made by a U-2 aircraft on October 22, 1964, and was studied by Penn [Ill. The aircraf6 flew over the eye a t levels of 50 mb., 115 mb., and 200 mb., and made a descent into it to about 300 mb. Although the eye region was 5"-6OC. warmer than the distant environment below 220 mb., the horizontal gradient of temperature and ozone became very weak just above the cloud tops a t 190 mb. The upper troposphere over the storm appeared to be slightly colder than the coastal environment. Another U-2 probe made into hurricane Isbell in October 1964, was also studied by Penn [12] who found that the tropopause was inclined

No abstract

No abstract