Table 38 (concluded) 223 



GEOSTROPHIC WIND, CONSTANT PRESSURE SURFACE 



200 geopotential foot contours 



where Am. is the contour spacing measured in degrees of latitude (i.e., one unit of An has 

 the length of one degree of latitude at the place for which the contour spacing is measured). 

 Table 38 gives values of V g in knots as a function of An and latitude with auxiliary 

 columns giving equivalents of An in kilometers, statute miles, and nautical miles. If the 

 latter are measured by a map scale true at some other latitude the value should be cor- 

 rected to the latitude at which the measurements are taken (see Table 165). 



Since the geostrophic wind is inversely proportional to the contour spacing and directly 

 proportional to the contour interval (A<£ gpft.), values of V„ for 1/10 of the indicated 

 spacing may be found by multiplying the tabular values by 10, etc., and for contour 

 intervals that are multiples or submultiples of 200 gpft. by multiplying the tabular values 

 by A$/200 (e.g., for 400 gpft. contours multiply by 2, for 100 gpft. contours multiply by 

 i, etc.). 



Contour spacing 



Degrees 



of Nauti- 



Lati- Kilo- Statute cal 

 tude meters miles miles 



1.0 111 69 60 



1.1 

 1.2 

 1.3 

 1.4 



1.5 

 1.6 

 1.7 

 1.8 

 1.9 



2.0 

 2.1 



2.5 

 2.6 

 2.7 



3.0 

 3.2 



3.4 

 3.6 



4.4 

 4.6 



5.0 

 5.5 

 6.0 

 6.5 

 7.0 



122 

 133 

 145 

 156 



167 

 178 

 189 

 200 

 211 



222 

 234 



2.2 245 



2.3 256 



2.4 267 



278 

 289 

 300 



2.8 311 



2.9 322 



334 

 356 

 378 

 400 



3.8 423 



4.0 445 

 4.2 467 



489 

 511 



4.8 534 



556 

 612 

 667 

 723 

 778 



8.0 890 



9.0 1001 



10.0 1112 



76 

 83 

 90 

 97 



104 

 111 

 117 

 124 

 131 



138 

 145 

 152 

 159 

 166 



173 



180 

 187 

 193 

 200 



207 

 221 



235 



66 

 72 

 78 

 84 



90 



96 



102 



108 



114 



120 

 126 

 132 

 138 

 144 



150 

 156 

 162 

 168 

 174 



180 

 192 



204 



249 216 

 263 228 



276 

 290 

 304 



240 

 252 



264 



318 276 



332 288 



345 300 



380 330 



415 

 449 



360 

 390 



Latitude 



50° 55° 



knots knots 



93.4 87.4 



84.9 79.4 



60° 



knots 



82.6 

 75.1 



65° 



knots 



79.0 

 71.8 



70° 75° 



knots knots 



76.1 74.1 



69.2 67.3 



80° 85° 



knots knots 



72.7 71.8 



66.1 65.3 



77.8 72.8 68.9 65.8 63.5 61.7 60.6 59.9 



71.9 67.2 63.6 60.7 58.6 57.0 55.9 55.3 

 66.7 62.4 59.0 56.4 54.4 52.9 51.9 51.3 



484 420 



553 480 

 622 540 

 691 600 



(To convert knots to other measures of speed see Table 35.) 



SMITHSONIAN METEOROLOGICAL TABLES 



