AEROGRAPHER'S MATE 3 & 2 



illustrated by lifting a parcel of air over a 

 mountain. Assume that a saturated parcel of 

 air having a temperature of 44° F is at 5,000 

 feet and is forced over a 12,000-foot mountain. 

 Condensation occurs from 5,000 to 12,000 feet 

 so that the parcel cools at the moist adiabatic 

 rate (3° F per 1,000 ft) and reaches a tempera- 

 ture of approximately 23° F at the top of the 

 mountain. Assuming that the condensation has 

 fallen out of the air during the ascent, the 

 parcel heats at the dry adiabatic rate as it 

 descends the other side of the mountain; when 

 it reaches the 5,000-foot level, the parcel will 

 have a temperature of approximately 61° F. 



Average Adiabatic Lapse Rate 



The average lapse rate lies between the dry 

 adiabatic and the moist adiabatic at about 3.3° F 

 per 1,000 feet. 



Super Adiabatic Lapse Rate 



The superadiabatic lapse rate is a decrease 

 in temperature of more than 5 1/2° F per 1,000 

 feet and less than 15° F per 1,000 feet. 



speed is the term that 

 of movement is meant. 



Direction 



is used when only rate 



Autoconvective Lapse Rate 



lapse rate is the 

 15° F per 1,000 feet. 



The autoconvective 

 decrease of more than . 

 This lapse rate is rare and is usually confined 

 to shallow layers. 



MOTION 



Any general discussion of the principles of 

 physics would be incomplete without some 

 consideration of the way in which mass, force, 

 and motion are related. We know from 

 experience that an object at rest never starts 

 to move by itself; a push or a pull must be 

 exerted on it by some other object. This 

 external force is needed because the body has 

 inertia. 



TERMS 



In dealing with motion, several terms are 

 commonly used, which should be defined before 

 venturing into the study of motion. They are: 



Speed 



The rate at which a body moves. It should 

 not be confused with velocity. In meteorology 



The line along which something moves or 

 lies. In meteorology, we may speak of direction 

 "toward" or direction "from". 



Velocity 



The term velocity describes both the rate 

 at which a body moves and the direction in 

 which it travels. 



Acceleration 



This is the term applied to the time-rate 

 of change of velocity. In relation to Newton's 

 Second Law of motion the following statements 

 are derived. 



1. For different forces acting upon the same 

 mass, different accelerations are produced that 

 are proportional to the forces, 



2. For different masses to acquire equal 

 acceleration by different forces, the forces 

 must be proportional to the masses. 



3. Equal forces acting upon different masses 

 produce different accelerations that are pro- 

 portional to the masses. 



LAWS OF MOTION 



The atmosphere, it is found, is constantly 

 in motion. This motion does not just happen of 

 its own accord; there are forces at work which 

 cause it to move. Some forces cause it to move 

 from one elevation, or height, to another as 

 convective currents. Other factors cause it to 

 move in various directions with a great range 

 of speed. Still other factors cause it to move 

 in either a clockwise or counterclockwise fashion 

 over wide areas. Perhaps a review of Newton's 

 laws of motion will aid the Aerographer's Mate 

 in understanding some of the reasons why the 

 atmosphere moves as it does. 



Sir Isaac Newton, a foremost English 

 physicist, formulated three important laws 

 relative to motion. In his first law, the law of 



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