10 

 Code Table IX 



Symbol A — Barometric tendency 



Code 

 figures 



Barometric tendency 



Barometer steady. (Has not fallen or risen more than 0.01 inch (}i millibar) in last 3 hours.) 



1 Barometer rising slowly. (Has risen 0.03 to 0.04 inch ( 1 to iy 2 millibars) in last 3 hours.) 



2 Barometer rising. (Has risen 0.06 to 0.10 inch (2 to 3% millibars) in last 3 hours.) 



3 Barometer rising quickly. (Has risen 0.12 to 0.18 inch (4 to 6 millibars) in last 3 hours.) 



4 Barometer rising very rapidly. (Has risen more than 0.18 inch (6 millibars) in last 3 hours.) 



5 Barometer falling slowly. (Has fallen 0.03 to 0.04 inch (1 to 1% millibars) in last 3 hours.) 



6 Barometer falling. (Has fallen 0.06 to 0.10 inch (2 to 3% millibars) in last 3 hours.) 



7 Barometer falling quickly. (Has fallen 0.12 to 0.18 inch (4 to 6 millibars) in last 3 hours.) 



8 Barometer falling very rapidly. (Has fallen more than 0.18 inch (6 millibars) in last 3 hours.) 



Code Table X 



Symbol a — Characteristic of changes of barometer in the last 8 hours 



Code 

 figures 



Description 



Rising, then falling 



1 Rising, then steady, or rising, then rising more slowly 



2 Unsteady 



3 Steady or rising 



4 Falling or steady, then rising; or rising, then rising more quickly. 



5 Falling, then rising 



6 Falling, then steady ; or falling then falling more slowly 



7 Unsteady 



Falling 



Steady or rising, then falling; or falling then falling more quickly 



Barometer now higher 

 than or the same as 3 

 hours ago. 



Barometer now lower than 



3 hours ago. 



