JOUENEYS THROUGH KOREA. 147 



The coast of Chifol-la-Do is notorious for its thick fog, es- 

 pecially in Jane. Being fringed with countless islands, usually 

 known by the name of the Korean Archipelago, in conjunction 

 with swift currents (2-5 knots), great tidal difference (14-293 

 feet), shallows, and thick fogs, it usually gives coasting steamers 

 hard work to get thro ugh. The fog^^ of the Chyöl-la-Do coast 

 and the South Yellow Sea have become proverbial, being com- 

 parable to that of the south coast of Hokkaido, the New Found- 

 land of the Pacific. The fog is generated either simply or as a 

 precursor of rain, both kinds appearing concomitantly with low 

 pressure. We may classify it according to the time of its occur- 

 rence into morning, afternoon, evening, and miduight fog. The last 

 is frequent in April, the second in May, and the first in June. The 

 fog is blown landwards by the sea-wind, sometimes changing into 

 drizzle which scatters within at most a quarter of an hour. 

 Ordinary fog iu which objects are visible at the distance of 10 m, 

 continues on an average for 11 hours in April, 5 in May, and 9 

 in July, though in exceptional cases it has been known to last 50- 

 60 hours. At the time of the generation of fog, the wind turns 

 from the east to the north-west or the reverse, and both cases 

 happen when a centre of low pressure passes over the south or 

 the north of the peninsula. 



As I have already said, the fog of the Chy'ôl-hi-Do coast is 

 blown landwards by the sea-breeze, being accompanied by a 

 lowering of pressure ; and during foggy weather the air pressure 

 approaches the monthly mean within the variation of ±3-4 mm, 

 and this is probably the condition essential to the generation of 

 the fog. The air temperature is above the monthly mean in 



1) T. Noda : "Fogs on tlie SoTitliern Yellow Sea." (in Japanese.) Jour. Meteor. Sac. 

 Japan. No. 7, Tokyo, 1905, p. 248. 



