Table 



10. Antarctic 



Ocean transparency (Secchi Disk) measurements. 







No. 



LCT 



Time 

 Zone 



Date 



Latitude 



Longitude 



Surface 



Water 



Temperature 



(degrees F.) 



Water Color 



Transparency 

 (feet) 





1 



1330 



11 



28 Dec 46 



64°12'S 



162°15'E 



31.4 



Green 



43 





2 



1600 



11 



28 Dec 46 



64°09' 



162° 15' 



30.8 



Blue-Green 



42 





3 



0830 



11 



30 Dec 46 



62° 13' 



159°11' 



33.9 



Blue-Gray 



40 





4 



1500 



11 



1 Jan 47 



59°06' 



150° 17' 



34.6 



Blue-Gray 



24 





5 



1330 



12 



4 Jan 47 



60°24' 



150°45' 



34.8 



Blue 



81 





6 



1500 



12 



5 Jan 47 



59°55' 



148° 50' 



34.3 



Blue-Gray 



23 





7 



1330 



12 



30 Jan 47 



68°43' 



174°55' W 



30.9 



Blue-Gray 



90 





8 



1300 



11 



11 Feb 47 



59°55' 



96°45' E 



36.8 



Blue-Gray 



55 





9 



1530 



6 



13 Feb 47 



60°55' 



88°55' 



36.5 



Blue-Gray 



41 





10 



1230 



6 



14 Feb 47 



60°52' 



84°30' 



35.3 



Green 



23 





11 



0915 



4 



19 Feb 47 



59°57' 



40°30' 



36.3 



Bright Blue 



68 





12 



1300 



4 



20 Feb 47 



61°14' 



37°40' 



37.5 



Blue 



85 





13 



1630 



3 



21 Feb 47 



60°45' 



29°45' 



37.2 



Blue-Gray 



55 





14 



1300 



4 



25 Feb 47 



60° 18' 



47°45' 



37.4 





47 





15 



1700 



6 



2 Mar 47 



63°55' 



82°20' 



30.6 



Green (at edge 

 of ice pack) 



32 





On clear days, icebergs stand out with such definition that 

 one feels he might reach out and touch them although they 

 are obviously many miles away. The topmost portion of 

 large bergs can still be seen when the base is so distant 

 that curvature of the earth causes it to appear well below 

 the horizon. The sun, which sets with little distortion or 

 change in color, is so brilliant that one cannot look directly 

 at it until it has almost entirely disappeared below the horizon. 



Even more impressive than the clarity of some of the 

 antarctic days, is the atmospheric transparency of many of 

 the antarctic nights. A strong beam of light is invisible 

 because of the absence of the Tyndall effect as there are no 

 solid particles in the air to scatter light. Stars shine brilliant- 

 ly and can be seen down almost as far as the horizon. Most 

 surprising is the fact that the stars shine with a bright steady 

 light and do not twinkle. All of this adds up to excellent 

 "seeing" -- probably unsurpassed anywhere in the world. 



This excellent "seeing" in the antarctic region is largely 

 understandable. As these regions are uninhabited areas 

 of water and ice, there is practically no source for inorganic 

 or organic dust particles, or for pollution by smoke. A 

 permanent high pressure area lies over Antarctica, so that 

 cold, dry, and consequently haze-free air flows radially 

 outward from the continent. Strong temperature inversions 

 cause the air to be stable and the airflow to be laminar. 



49 



