44 



developed disturbances. The first line of discontinuity to sweep 

 across the observer's position is termed the warm front and this 

 carries along with it the greatest abundance of precipitation. Coin- 

 cident with the passage of the warm front the winds haul abruptly 

 and also abate in force. The warm sector is characterized by warm 

 moisture-laden air, overcast skies, reduced visibility, less intense winds 

 and occasional rain showers. The second line of discontinuity is called 

 the cold front and squall line. The direction of the wind at this place 



Fig. 8.— The structure of a cyclone 



changes quickly to the right, the temperature drops precipitously, 

 and the skies clear. The cold front is often accompanied by rain or 

 hail squalls and perhaps also thunder and lightning and a strengthen- 

 ing of the wind. All of these are interesting to follow : The barograph 

 curve, the wind velocity and direction, the air temperature, and the 

 precipitation during the passage of some of the storms we experience 

 on patrol. Often one can preceive how definitely, even in a crude 

 way, the general structure of a cyclone can be traced. 



