B, Upper Level Tropical Cyclone, The second category of weather situation, the upper level tropical cyclone, is very easily confused with the first; especially if an adequate upper air observational network is not in operation, In the lower atmosphere the winds lie, as in the trade situation, between east-northeast and northeast, The fluctuations in speed, time, and space may be quite large, however, and the winds do not vary latitudinally in the regular manner that is typical of the trade situation. It has been observed, for example, that although the winds remain in the northeast, the entire Marshalls areas may show wind speeds of less than ten knots for a period of two or three days. The cloud cover, instead of being recorded as 5/10 trade cumulus, may consist of only 2/10 to 4/10 of small cumulus below 4,000 feet over most of the area. Here and there, a more or less stationary line of large cumulo-nimbus with heavy showers~-or even thunderstorms on occasion-—may be seen lying across individual atolls or may be observed from aircraft, The greatest dif- — ference lies, however, not in the lower cloud but in the middle and upper regions, A very extensive sheet of alto-stratus breaking here and there to alto-cumulus will blanket the southern Marshalls and extend from time to time to the latitude of Miwetok and Bikini. From this sheet, wherever it is thick, will fall a continuous and oftentimes heavy rain, Cirrus cloud is much more extensive than normal and in the south may form a continuous overcast layer lying above and sometimes fusing with the alto-stratus decks, 167 Cloud and