12 OCEANOGRAPHY IN THE UNITED STATES 



droughts or flood-producing rains, or destructive storms; or to detect 

 and locate incipient tornadoes and weather factors decisive in national 

 defense plans, then we must first collect essential atmospheric data 

 and analyze and understand the mechanisms or natural processes that 

 produce the changes in weather and climate and generate storms. 



I have already spoken of the fact that great gaps exist in our data. 



I am going to bring up tins chart a little bit closer. This simply 

 shows as an illustration the weather map of the Northern Hemisphere 

 to show how certain weather phenomena are interrelated. 



This is a polar projection. Here is the North Pole, North America, 

 Siberia, Alaska, and Europe. There are low pressure patterns 

 alternating here. These circles show low pressure patterns and 

 what one does afi^ects what the others do. Tliere are high pressure 

 centers here over Greenland and the Arctic area and down here in 

 Eastern Europe and so on. This whole thing operates more or less 

 as an integrated mechanism. 



Hurricfines are one of the most destructive storms. 



Here are the tracks of August hurricanes for 30 years. As I 

 illustrated earlier, they form near tlie coast of Africa. Sometimes 

 they move across and come up across the Gulf and affect the Gulf 

 coast. Sometimes they affect the Atlantic coast. Sometimes they 

 recurve at sea and do not affect the continental regions at all. 



What is the reason that they behave in tliese different fashions? 

 It depends, so far as we know, on the general circulation to a large 

 extent, although there may be a mechanism within the storm that has 

 more to do than we at present know about the direction of movement 

 of the storm. 



The next chart sliows 



Mr. Miller (presiding). Doctor, you show where the}' originate 

 or where you pick them up out there in the South Atlantic off the 

 coast of Africa. You say that you think they originate in the Sahara 

 some place? 



Mr. Reichelderfer. Not all of them. 



Mr. Miller. You have no data from that country? 



Mr. Reichelderfer. This is improving. We are getting some re- 

 ports from the Sahara. The African countries are developing their 

 meteorological services and we do receive some reports, although, 

 of course, not nearly enough. I would, just as a guess, say that less 

 than 5 percent of our hurricanes actually originate over Africa. They 

 iirst sliow up in what we call a wave usually on a front, just a little 

 l)ulge in the isobars which are the pressure lines. You can follow 

 that from day to day as it moves acioss. 



These waves occur frequently. If conditions are favorable — and 

 we do not know just what the conditions are — it will develop into a 

 circular storm with the counterclockwise winds all around the low 

 ])ressure area, and then it may generate into a very severe storm. 



Your question, sir, asked about origin. Some of them generate 

 here, some around here, but we know very well that som(> generate* 

 riglit in the Gulf just off tlie coast. Tliey will blow up in 12 or 24 

 hours and become a severe storm. 



We have quite an extensive research project, the National Hurricaiu> 

 Research Project. In this project, we fly aircraft into tlu^ hurricane. 

 We are trying to get the JueasurenuMits of the wind, th(> humicUl.w tlie 

 temperatures, and other factors that enter into the generation of these 



