Atmospheric Correction; Hpa And Mmhg Conversion Table - Pentax R-2501NS Instruction Manual

12.2 Atmospheric correction

The speed at which light travels through the air varies depending on the temperature and
atmospheric pressure. The R-2500NS series is designed to measure distances at the speed of
light. In order to measure accurately, atmospheric correction needs to be used. The instrument
is designed to correct for weather conditions automatically if the temperature and pressure are
input. Correction is then carried out based on the following formula.
Calculation formula
K= (276.26713 –
K: Atmospheric Correction Constant
P: Atmospheric pressure (hPa)
t: Temperature(° C)
Distance after Atmospheric Correction D = Ds (1+K)
Ds: Measured distance when no Atmospheric Correction is used.

12.3 hPa and mmHg conversion table

[Converting from hPa to mmHg]
hPa 0 10
500 375 383
600 450 458
700 525 533
800 600 608
900 675 683
1000 750 758
1100 825 833
1200 900 908
[Converting from mmHg to hPa]
mmHg 0 10
400 533 547
500 667 680
600 800 813
700 933 947
800 1067 1080
900 1200 1213
78.565271・P
-4
273.14941 + t ) 10
X
273.14941 + t
20 30 40
390 398 405
465 473 480
540 548 555
615 623 630
690 698 705
765 773 780
840 848 855
915 923 930
20 30
560 573 587
693 707 720
827 840 853
960 973 987
1093 1107 1120
1227 1240 1253
50 60
413 420
488 495
563 570
638 645
713 720
788 795
863 870
938 945
40 50 60
600 613
733 747
867 880
1000 1013
1133 1147
1267 1280
Unit:mmHg
70 80 90
428 435 443
503 510 518
578 585 593
653 660 668
728 735 743
803 810 818
878 885 893
953 960 968
Unit:hPa
70 80 90
627 640 653
760 773 787
893 907 920
1027 1040 1053
1160 1173 1187
1293 1307 1320
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