AEROGRAPHER'S MATE 3 & 2 



GLACIER WIND. A shallow gravity wind along 

 the icy surface of a glacier, caused by the tem- 

 perature difference between the air in contact 

 with the glacier and the free air at the same 

 altitude. 



HORSE LATITUDES. The belts of latitude over 

 the oceans at approximately 30° - 35° N and S 

 where winds are predominantly calm or very 

 light and the weather hot and dry. 



HURRICANE. A severe tropical storm in the 

 North Atlantic, Caribbean, Gulf of Mexico, and 

 Eastern North Pacific east of 180° longitude, 

 whose wind speed is more than 63 knots. 



INVERSION. A departure from the usual in- 

 crease or decrease with altitude of the value 

 of an atmospheric property. 



ISALLOBAR. A line of equal change in at- 

 mospheric pressure during a specified time 

 interval. 



ISOHALINE. A line of equal or constant 

 salinity. 



ISOPLETH. A line of equal or constant value 

 of a given quantity. 



ISOTACH. A line on a given surface connect- 

 ing points of equal wind speed. 



ISOTHERM. A line of equal or constant 

 temperature. 



ISOTHERMAL. Of equal or constant tempera- 

 ture, with respect to space or time. 



KATABATIC WIND. Any wind blowing down 

 an incline; the opposite of anabatic. 



LAND BREEZE. A coastal wind blowing from 

 land to sea, caused by the temperature dif- 

 ference when the sea surface is warmer than 

 the adjacent land. Usually occuring at night. 



LAYER DEPTH. The thickness of the mixed 

 layer; or the depth to the top of the thermocline. 



LOOMING. A mirage effect produced by 

 greater-than-normal refraction in the lower at- 

 mosphere, thus permitting objects to be seen 

 that are usually below the horizon. 



MACKEREL SKY. A sky with considerable 

 cirrocumulus or small-element altocumulus 

 clouds, resembling the scales on a mackerel; 

 clouds of the variety vertebratus. 



MERIDIONAL FLOW. A type of atmospheric 

 circulation pattern in which the meridional (north 

 and south) component of motion is unusually 

 pronounced. 



MIRAGE. A refraction phenomenon wherein 

 an image of some object is made to appear 

 displaced from its true position. 



MIXED LAYER. The surface layer of vir- 

 tually isothermal water. 



MONSOON. The name for seasonal winds 

 caused primarily by the much greater annual 

 variation of temperature over large land areas 

 compared with the neighboring ocean surfaces, 

 causing an excess of pressure over the continents 

 in winter and a deficit in summer. 



MOUNTAIN WIND. The wind that descends 

 a mountain valley at night; a katabatic wind. 



OROGRAPHIC LIFTING. The lifting of an 

 air current caused by its passage up and over 

 a mountain. 



POLAR FRONT. The semipermanent, semi- 

 continuous front separating air masses of tropical 

 and polar origin. This is the major front in 

 terms of air mass contrast and susceptibility 

 to cyclonic disturbance. 



POTENTIAL TEMPERATURE. The tempera- 

 ture a parcel of dry air would have if brought 

 adiabatically from its initial state to the standard 

 pressure of 1000 mb. 



PRESSURE GRADIENT. The rate of decrease 

 (gradient) of pressure in space at a fixed time. 



RADIATION FOG. A major type of fog, pro- 

 duced over a land area when radiational cooling 

 reduces the temperature to or below its dew 

 point. 



SEA BREEZE. A coastal wind that blowsfrom 

 sea to land, caused by the temperature dif- 

 ference when the sea surface is colder than 

 the adjacent land. Usually a daytime occu; ....'.e. 



SHEAR LINE. A line or narrow zone across 

 which there is an abrupt change in horizontal 

 wind component parallel to this line; a line 

 of maximum horizontal wind shear. 



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