1) Location
2) Landmass
1) Location
Poised strategically in the northeastern part of the Asian continent, the Korean Peninsula thrusts in a southerly direction for about 1,000 kilometers. To the north are regions of China and Russia, while the Chinese mainland lies directly to the west. To the east, the peninsula faces the islands of Japan. The closest point from Korea to China is China's Shantung Peninsula which lies 190 kilometers. The closest point in Japan is the island of Honshu which lies in 180 kilometers from Korea's southern port of Pusan. With its north-south elongation, Korea separates the Yellow Sea from the East Sea. The Korean Peninsula and all of its associated islands lie between 124 degrees, 11 minutes, and 00 seconds E and 131 degrees, 52 minutes, and 42 seconds E and between 33 degrees, 06 minutes, and 40 seconds N and 43 degrees, 00 minutes, and 39 seconds N.
The land boundary between China and Korea is largely formed by two rivers: the Amnokkang River (Yalu River in Chinese) and the Tumangang River (Tumen River in Chinese). The last 16 kilometers of the Tumangang River also serve as a boundary with Russia. The Amnokkang River flowing southwest empties into the Yellow Sea; the Tumangang River first flows northeast and then southeast, emptying into the East Sea. The Peninsula, contiguous to the two continental powers of China and Russia and adjacent to oceanic Japan, long acted as a land bridge over which continental cultures were transmitted to Japan. The peninsular location brought not only the advantage of easy access to adjacent cultures but also the disadvantage of furnishing a target for aggressive neighbors.
2) Landmass (Area)
The area of Korea is 221,607 square kilometers (about 85,563 sq. miles). At present, the land is divided into two parts: the Republic of Korea (South Korea) and the People's Republic of Korea (North Korea). The administrative area of the Republic of Korea is 99,237 square kilometers or about 45 percent of the whole of Korea. South Korea is slightly larger than Hungary or Portugal, and a little smaller than Iceland.
Administrative and Traditional Regions
Regional variations of Korea are greater than one might expect, partly because of topographical diversity and partly because of historical developments over a long period. From the early days of the Choson Dynasty (1392 - 1910) up to the year of 1896, Korea was divided into eight administrative provinces: Hamgyong-do, P'yongan-do, Hwanghae-do, Kyonggi-do, Kangwon-do, Ch'ungch'ong-do, Cholla-do, and Kyongsang-do. These eight provinces were subdivided into 13 provinces in 1896, and eight of the 13 provinces currently are in South Korea. After 1945, Chejudo Island became an independent province, and Pusan, Taegu, Inch'on, Kwangju, and very recently the Taejon metropolitan areas took on a status equivalent to provinces directly under the central government. Seoul, the capital of South Korea, is the only special city, which is administratively higher than a province. Thus, the Republic of Korea is comprised of one special city, five metropolitan areas, and nine provinces. The nine provinces are subdivided into 55 cities (shi) and 138 counties (gun).
Korea also may be divided into six larger traditional regions: Kwanbuk on the east and Kwanso on the west, now part of North Korea; Kiho, roughly the area of Kyonggi-do province, and a part of the Ch'ungch'ong-do province; Kwandong, a part of Kangwon-do province, east of the T'aebaek mountain range; Honam, the area comprising a part of the Ch'ungch'ong-do and all of the Cholla-do provinces; and Yongnam, the Kyongsang-do provinces. Minor differences are found in dialects and customs among the six traditional regions.
Population
In mid-1992, South Korea had a population of 43,663,000, and a density of 440 persons per square kilometer. The population of North Korea was estimated at 22,672,000 in 1992 according to a UN projection. As a whole, the population of the Republic of Korea increased rapidly after World War II. Before World War II, Koreans migrated to two major regions, Manchuria and Japan. Today, there are more than two million Koreans in Manchuria and 600,000 Koreans in Japan. The close relationship between Korea and the United States after World War II resulted in a sizable number of Koreans moving to that country. It is estimated that more than 1.5 million Koreans now live in the United States. The most important internal migration in recent times occurred in the years of 1945 to 1953, especially during the Korean War (1950 - 53). It is estimated that about two million people have migrated from North Korea to South Korea since 1945. There are no significant racial minorities in Korea.
Since 1960, Korea has experienced a dramatic slowdown in population growth and consequently is undergoing rapid demographic transition. The birth rate had remained steady at a level of 40 births per thousand people every year, until 1960. This high fertility rate may be explained partly by little or no population control. There were also other causes for the high fertility rate such as the tendency to marry at a yuong age and the Korean system of matchmaking. With the nation's systematical pursuit of its socio-economic development in 1962 through its first five-year plan, measures for population control and family planning were incorporated as an integral part of its formal development plan. Owing to the successful implementation of the population control programs, the birth rate began to decline rapidly from about 42 per thousand people in 1960 to 30 by 1970, but leveled off during the 1967 - 72 period, perhaps due to the threshold effect. The birth rate further declined to 22 per thousand people by 1982. Since the early 1980s, there was another sharp drop in the birth rate to 16.4 in 1985, and the rate remained at this level until recently. The total fertility rate in Korea has declined sharply, from 6.0 births per woman in 1960 to 4.5 births in 1970, to 2.7 births in 1980, and to the population replacement level of 2.1 births in the mid-1980s. The total fertility rate further declined and reached 1.6 births per woman in 1992.
The changes in mortality rate in Korea have been more moderate but have steadily declined over the years. The death rate declined from 12.1 per thousand people in 1960 to 6.7 in 1980 and 5.9 in 1992.
Consequently, the rate of population growth has also shown a gradual and steady downward trend, to less than 1 percent in 1992 from 3 percent in 1960. Therefore, Korea has reached below its replacement level in the demographic transition, and the current low level of total fertility rate will remain within the range of 1.5 to 2.0. The Korean population is expected to grow at a moderate rate to 46.8 million and 49.7 million in 2000 and 2010 respectively. The Korean demographic transition is expected to be completed in 2020.
Demographic changes in Korea have caused drastic changes in its population structure in the past three decades. During the past 30 year period, from 1960 to 1992, the proportion of the population aged 14 and less decreased from 42.3 to 24.8 percent while that of 15 - 64 increased from 54.8 to 70.0 percent, resulting in a decreased child dependency ratio, from 77.3 to 35.5 percent. The population between the ages 15 and 64 is expected to increase continously, but slowly until around 2000, when the proportion will reach its peak at 72.2 percent, and decline slowly thereafter. At the same time, as a result of continuously declining fertility rates, the absolute size as well as the relative proporiton of the young population below the age of 15 will continue to decrease. The composition of the aged population over 65 has steadily increased over the years with prolonged life expectancy due to socio-economic development. The proportion of the aged in Korea remained around 3 percent in 1960 and 1970, and gradually increased to 3.8 percent and 5.2 percent in 1980 and 1992, repectively. However, this ratio is expected to rapidly grow in the next century reaching 6.8 percent in 2000 and doubling to 13 percent by 2020.
Settlement and Urbanization
Rapid industrialization in Korea since the early 1960s has accompanied drastic changes in the spatial distribution of human settlements. The urban population in Korea, which accounted for only 28.0 percent of the total population in 1960, doubled to 57.3 percent in 1980 and further increased to 74.4 percent in 1990, primarily due to rural-to-urban migration. The number of cities has also increased. There were only 12 major cities in 1945. Today there are six metropolitan areas, namely Seoul, Pusan, Taegu, Inch'on, Kwangju, and Taejon, and 68 local cities.
Metropolitan growth and urbanization have been most pronounced in the two metropolitan cities of Seoul and Pusan. The population of the capital city of Seoul increased more than four-fold from 2.4 million in 1960, to 10.6 million in 1990 while in Pusan, the population increased from 1.2 million in 1960 to 3.8 million in 1990. From the early 1980s, the population concentration in the two metropolitan cities began to show a new trend: while the population decreased slightly in Seoul between 1985 and 1990, it increased in Pusan moderately throughout the 1980s. Seoul's surrounding satellite cities had experienced the most population growth. Consequently, the Seoul metropolitan area had 42.8 percent of the total population in 1990, and the Pusan metropolitan area followed with approximately 17.3 percent. Altogether, 60.1 percent of the 1990 population lived in these two major metropolitan areas.
Rapid urbanization in Korea has resulted from rapid industrialization. The industrialization process strategy Korea employed since the early 1960s was an outward oriented one. The Korean Government promoted export-oriented light manufacturing in the initial stage of industrialization and heavy and chemical industries in the latter stage due to its weak agriculture base. In the process of transforming a typical agricultural society to an industrial one, massive migration from rural areas to urban industrial centers resulted. To accomodate the influx of rural population, major cities expanded their boundaries; furthermore, industrial towns grew and evolved into new cities, accelerating urbanization.
Consequently, growth of cities became self-propelling with their continuously expanding employment opportunities and their concentrations of public and private institutions ranging from financial and commercial to educational and cultural. Such a concentration of the nation's best institutions in major cities was another important factor in rural-to-urban migration in Korea. Because of excessive concentration in the two Korean megalopolises, real estate prices have become prohibitively high and discouraged rural-to-urban migration in recent years. The absolute population size of Seoul thus decreased from 1985 to 1990. On the other hand, the neighboring small cities and towns of Seoul and Pusan have recently experienced the highest population growth rates.
As a result of the rapid urbanization after World War II, Korea has a small rural population, 25.6 percent in the 1990 census. As most of the rural population engages in agriculture, it is highly concentrated in the lowlands of the west and south coasts along the major river valleys. Agglomerated villages are common in rural areas with a few exceptions in mountainous regions and in areas of reclaimed land on the west coast. In agglomerated villages, farming activities, such as transplanting rice from seabeds, and harvesting and threshing rice are often carried out through the cooperative effort of the villagers. However, farm mechanization has resulted in changes in many agricultural activities, and recent farm labor shortages are arising mainly due to excessive rural-to-urban migration of young people.
Rural villages are usually located in the foothills and face southward. Such a location provides protection from the severe cold winter monsoons, and allows maximum use of the lowland for cultivation. The location of settlements and houses has also been influenced by geomancy, according to which the ideal site for a house or village has a hill behind it and faces a stream. Consequently, topographic maps usually show villages along the boundaries between hills or mountains and plains or river valleys.
The Saemaul Undong (New Community Movement) and the introduction of farm machinery have resulted in a gradual changing of the rural landscape. Farm villages are being developed into well-organized communities with a systematic arrangement of houses, increasingly constructed of cement and tile. Most straw-thatched houses disappeared during the 1970s. The use of wood fires for heating in the rural areas is decreasing rapidly with the increasing use of coal and in recent years gas. However, the most significant change in the rural areas had been a rapid decrease in population and a subsequent shortage of farm labor.
It is likely that the urbanization in Korea is anticipated to continue moderately in the near future. Evidence in the 1980s suggested that the net migration to metropolitan areas decreased rather sharply and that Kyonggi-do Province surrounding the capital city had attracted the most inter-province migrants during the same period. In view of the prevailing reasons for migration, the promotion of balanced regional development and the reduction of the urban and rural disparities in socio-economic conditions are necessary in order to alleviate the urbanization trend in Korea.
1) Land Forms
Korea is geomorphologically characterized by abundant hills and mountains, which occupy nearly 70 percent of its territory. Low hills, located mostly in the south and the west, give way gradually to increasingly higher mountains toward the east and the north. On the whole, the western and southern slopes of the Korean Peninsula are gentle with various types of plains, low hills, and basins developed along the rivers. The eastern slope is steep with no significant rivers or plains because high mountains are close to the coast. The western and southern coasts are highly indented with innumerable islands, but the eastern coast is generally smooth with few islands.
2) Mountains
The mountain ranges of Korea run in two major directions, north-to-south and northeast-to-southwest. The ranges of the north-to-south masses, the T'aebaek range in South Korea and the Nangnim range in North Korea, form the geological backbone of the Peninsula and constitute the drainage divide between the western and the eastern slopes. Many summits such as Mt. Nangnimsan (2,014m), Mt. Kumgangsan (1,638m), Mt. Soraksan (1,780m), and Mt. T'aebaeksan (1,546m) are located along the dividing ridge of the two mountain ranges. The Kumgangsan and Soraksan mountains are renowned for their scenic beauty. They have various spectacular land forms carved out of granite rocks, a series of rocky pinnacles piercing the sky, deep and narrow canyons bordered by nearly vertical granite walls and numerous waterfalls and rapids along the streams. The two mountain ranges, however, have been a great barrier to communication between the eastern and the western sides of the Peninsula since early times.
Smaller mountain ranges, originating in the Nangnim and the T'aebaek regions, run parallel to each other in a northeast-to-southwest direction. They are, from the north, the Kangnam, the Choegyu, the Myohyang, and the Myorak ranges, all located in North Korea. The Hamgyong range in North Korea and the Sobaek in South Korea also have their roots in the north-to-south ridge mountains and run in a generally northeast-to-southwest direction.
The parallel mountains on the western slope are mostly a series of continuous high hills, especially toward the west coast, offering no significant barriers to communications between the lowlands. However, the relatively high Sobaek range historically has obstructed free intercourse between the central and the southern regions and also between the eastern and the western districts in the southern region. Mt. Chirisan (1,915m) is the highest summit in the range.
It is believed that most of the Peninsula was an erosional lowland until the middle of Mesozoic era, when it began to undergo an uplift. The rate of uplift was increasingly greater toward the east, and the effect was even negative in the west. A periglacial and arid climate during the Pleistocene era is supposed to have accelerated erosion of the land surface. As a result, the land forms that have evolved show mature development with relatively large relief along the T'aebaek mountain range, but moving away from there, subdued hills with small relief become gradually prominent. In fact, low hills, which appear to be in the old stage, characterize most of the Peninsula. The so-called "roof of Korea," the Kaema Plateau, has an average elevation of about 1,500 meters above sea level, and Mt. Paektusan, the highest mountain on the Peninsula and located in the northwestern corner of the plateau, has an altitude of 2,744 meters above sea level.
The Peninsula is a rather stable land mass in spite of its proximity to Japan, so that Korea has neither active volcanoes nor strong earthquakes. There are a few extinct volcanoes that are believed to have been formed between the late Tertiary and early Quaternary periods. Mt. Paektusan is famous for a large crater lake called Ch'onji, meaning "Heavenly Lake," which is located at its summit. Mt. Hallasan (1,950m) on Chejudo Island, the highest mountain in South Korea, has a record of minor volcanic activity during the middle of the Koryo Dynasty (918 - 1392 A.D.). It has a small crater lake called Paegnoktam and is peculiar in that it has more than 360 parasitic cones.
Volcanic activity during the geological past also developed several lava plateaus including the Shinge, Koksan, Chorwon, and Kaema. Streams usually cut narrow channels with high and vertical walls in these flows due to the columnar joints in the lava, resulting in a picturesque landscape. Chejudo Island, especially, has numerous lava tunnels and sea cliffs.
Korea has a relatively wide distribution of pre-Cambrian metamorphic rocks and Paleozoic sedimentary rocks and granite gneiss, of which limestone is one of the most common. Accordingly, there are many karstic areas, many of which are known for their caves. T'ongnyonggul, near Yongbyon on the southern side of the Ch'ongchongang River in North Korea, is the most famous cave. It is about 5 kilometers long and several of its chambers are nearly 150 meters wide and 50 meters high. There are also a number of limestone caves in South Korea. Among the most famous are Kossigul, Kosudonggul, Songryugul and Hwangsonggul. All of these caves have stalagmites and stalactites, ponds, and streams.
Korea does not have mountains high enough to maintain glaciers or ice caps. However, during the Pleistocene era, when most of the continents of the northern hemisphere were repeatedly glaciated, some alpine glaciers developed in a few summit area of the Hamgyongsan and the Mach'ollyongsan mountains, leaving some erosional features such as small cirques. However, no depositional forms are found. Mt. Paektusan (2,744 m), Mt. Kwanmosan (2,541 m), and Namp'odaesan (2,434 m) show such forms. It is estimated that the snow line at the time of their development was approximately 2,000 meters. Recently, patterned soil and solifluction, which indicate strong periglacial phenomena during the Pleistocene era, have been found below the snow line.
Rivers
Most of Korea's major rivers flow into the Yellow Sea and the South Sea after draining the western and southern slopes of the Peninsula. Considering the size of its territory, Korea has a relatively large number of streams. Six rivers exceed 400 kilometers in channel length -- the Amnokkang River (790 km), the Tumangang River (521 km), the Hangang River (514 km), the Kumgang River (401 km) and the Naktonggang River (525 km). The first two rivers constitute international boundaries with China and Russia and flow into the Yellow and East seas respectively. The Naktonggang river flows into the South Sea and the rest into the Yellow Sea. Their flow volume, which are to a great extent related to summer monsoons, fluctuate from season to season. In summer, the rivers swell with rainfall accompanying the monsoon, often flooding valley plains once or twice every year. In the other seasons, which are relatively dry, the water level becomes very low, and often much of the river beds become exposed. Typhoons normally hit South Korea along the coast of the South Sea, bringing heavy floods in late summer and early autumn.
The gradient of longitudinal river beds is mostly low in the lower reaches of the major streams, permitting navigation for quite long distances from river mouths. Accordingly, rivers have played a significant role in life-styles since early times. Most historical capital cities such as Seoul, P'yongyang, and Puyo developed on major navigable rivers. After the introduction of railroads and automobiles, the importance of rivers in terms of transportation decreased sharply. Rivers are now used extensively for irrigating rice fields. River irrigation has been much accelerated in recent years as a result of the introduction of modern technology. Previously only small tributaries could be dammed for the purpose of irrigation, but now more than 72 percent of rice fields depend on rivers for irrigation. Many large scale multipurpose dams for flood control, generation of hydroelectricity, irrigation, and etc. have been constructed or are under construction at various sites on all rivers in South Korea.
Plains and Basins
There are few large plains in Korea, but relatively wide plains are found on the west coast along the rivers. The overall elevation of these plains is low, and the effect of the sea level rise during postglacial times is noticeable, especially around river mouths. The plains have developed as a result of sedimentation after the sea level approached its present position. As a result, the plains appear wide compared with the associated rivers, but the alluvial deposits form relatively thin cover. These fertile plains are Korea's major rice-producing regions. The wide coastal plains near the river mouths change abruptly into narrow flood plains a short distance upstream. Large tidal ranges and funnel-shaped river mouths do not allow the formation of active deltas forming out into the sea, although rivers transport large amounts of silt during floods
Along the east coast, which has only small streams flowing from the T'aebaek mountain range to the coast, narrow strips of alluvial beaches can be found. The Naktonggang River flowing into South Sea has a relatively large delta at its mouth. Most of the delta is confined within the river valley, but is gradually advancing into the sea
Besides coastal alluvial plains, erosional basins formed at the junctions of large streams inland have been widely utilized as major agricultural regions since ancient times. Ch'unch'on, Ch'ungju, and Wonju are examples of old towns developed in such places. The lowland of the basins is usually the site of erosionally weak granitic rock, and the mountains and hills on their periphery consist of highly resistant metamorphic rocks, such as gneiss and schist.
The wide range of temperature fluctuation and concentrated rains in summer induce intense weathering and erosion of rocks. Gentle slopes at the foot of mountains and hills around the basins are covered with thick deposits of weathered materials washed down from the steep upper slopes. Alluvial fans are seldom developed, even though rock fans covered with thin sediment are often discovered.
The Coasts, Islands, and Seas
There are about 3,000 islands off the coast of Korea, most of them in southern and southwestern coastal areas. The total length of coastline is estimated at 17,300 kilometers. The coastal length of the peninsular portion is about 8,700 kilometers and that of the islands about 8,600 kilometers. Korea's coastline is long compared to its total land area because there is much indentation. The east coast has a relatively smooth coastline, except for the Yonghung and the Yongil bays, because of mountains running parallel and close to it. However, there are some variations in land forms. Where the mountains are close to the sea, the coast is rocky with few beaches. Sea cliffs and stacks characterize the coasts between Hungnam and Songjin and between Kangnung and P'ohang. Haegumgang is one of the rocky coasts located adjacent to Mt. Kumgangsan. Beaches are found where small streams discharge into the sea. In many instances, they take the form of sand spits and bars enclosing coastal lagoons. Along the coast between Wonsan and Kangnung, there is a series of lagoons of which Kyongp'o and Hwajinp'o are among the most famous. With improved roads and transportation facilities, the east coast attracts many tourists in summer due to the lovely scenery and clean beaches. There are a few islands along the coast. Ullungdo, a volcanic island, is the largest.
In contrast with the east coast, the south and the west coasts are very irregular with innumerable islands, small peninsulas, and bays. The west coast facing the Yellow Sea has a large tidal range (6 - 9.3 meters at Inch'on) and a shallow offshore bottom. Tidal flats, mostly composed of mud, are extensive, especially near the river mouths. As a result, water is murky throughout the year. Tidal flats are under extensive reclamation for agricultural land and salt pans.
The south coast is typically Riasic. The islands are the remnants of inundated hills, and the bays extend to the inundated valleys. The length of coastline is nearly eight times longer than its straight-line distance, and its indentation is far greater than that of the west coast. The tidal range of the south coast is between those of the west and the east. The tidal range is relatively small -- 1.3 meters at Pusan on the eastern side and 4.9 meters at Yosu in the center of the coast. Tidal flats are not as wide as on the west coast. Although mountains face the sea, there are few sea cliffs because innumerable islands prevent much erosive wave action along the mainland coast. Narrow tidal channels between islands are associated with extremely rapid tidal currents. At Ultolmok toward the western end of the south coast, the current reaches up to 7.5 knots, the highest recorded in Korea. The largest island in Korea is Chejudo, which is located about 140 kilometers south of Mokp'o.
The depth of the Yellow Sea and the South Sea is less than 100 meters; therefore, their sea floors form a shallow continental shelf. These shallow seas are important for fisheries. Recently, explorations for petroleum in the continental shelf have been undertaken.
A branch of the warm Kuroshio Current, which comes from the east coast of the Philippines, splits into two near Chejudo Island, one current flowing into the Yellow Sea and the other into the East Sea. The Yellow Sea Current flows northward along the west coast and back southward along the east coast of China. It is a weak current due to the shallowness of the sea, with no significant influence on winter temperature. However, the Tonghan (East Korean) Current, which flows northward along the east coast after passing the Korea Strait, is very strong and has a high temperature gradient compared with adjacent waters. It flows in an eastward direction from near Chukbyon toward Ullungdo Island. In summer, however, its influence reaches farther north to Tonghan Bay.
A cold current, the Pukhan (North Korean) Current, flows southward along the northeastern coast, and is a branch of the Liman Current coming from the Okhotsk Sea. Its strength becomes greater in winter and its influence reaches farther south, pressing the warm Tonghan Current to lower latitudes. Thus the East Sea near the coast, which has a seasonal interchange of cold and warm currents is excellent for fishing. Most of the east coast has warmer temperatures in winter than the west coast due to the influence of the winter monsoon and warm current.
Climate
1) Continental Influence on Climate
The nature of Korea's climate is defined by its midlatitudinal location and peninsular configuration, as well as its position as an appendage to the world's largest continent, Asia, and is influenced more by the continent than the ocean. Korea has a humid, East Asian monsoonal climate. The mean temperature during winter is generally below freezing. The mean temperature in January in Seoul is 3.5 degrees C. below freezing, while that of London is 4.6 degrees C. above freezing, and that of San Francisco is 10.1 degrees C. Summer in Korea is hot. In most of the country, the mean temperature of hottest month is above 25 degrees C. except in the northern interior. The mean temperature of the hottest month for Seoul is 25.3 degrees C. The annual temperature range between the coldest and hottest months for Seoul is about 28.3 degrees C. The range of temperature is much greater in the north and in the interior than in the south and along the coasts.
2) Monsoon and Rainfall
Korea is located in the East-Asian monsoon belt. During the winter months, continental high pressure air masses develop over inland Siberia, from which strong northwesterly winds bring dry, cold air into Korea. The winter monsoon, usually stronger than the summer one, causes much hardship. The summer monsoon brings abundant moisture from the ocean, and produces heavy rainfall. About 70 percent of the annual rainfall comes during June through September. Heavy showers with thunder and lightning are common. In addition, passing cyclonic storms add still more rainfall. Annual precipitation varies from 500 millimeters in the northeastern inland areas to 1,400 millimeters along the southern coast. The amount of rainfall decreases from the south to the north. The middle and upper parts of the river basins of the Somjingang River, Hangang River, and Ch'ongch'ongang River are areas of comparatively heavy rainfall, partly because of the convergence of wet airflows along the river valleys and the orographic uplift of the air flows. The southern coastal belt and the islands of Chejudo and Ullungdo also are heavy rainfall areas which receive about 1,400 to 1,500 millimeters annually.
The winter monsoon, which originates in the interior of the Asian continent, is dry and low in temperature. It produces little precipitation except for a few winter snowfalls. The winter months normally receive less than 10 percent of the total annual precipitation. Seoul receives about 126 millimeters of precipitation during the winter months, December to March, which is less than one third of the amount of rainfall for July -- 383 millimeters.
There are great variations in precipitation from year to year. According to 178 years of precipitation records, the maximum annual precipitation in Seoul was 2,135, recorded in 1940; the minimum was 633.7 millimeters, in 1949. The statistics show that about once every eight years, annual precipitaion falls below the 1,000 millimeters mark, which is usually considered the minimum for rice cultivation where no irrigation is available. This explains why in the days of an insufficient irrigation system the Seoul area would have a rice crop failure once every eight years.
3) Storms and Typhoons
There are two types of storms which affect the climate of Korea. One originates in the Yangtze Valley and usually passes Korea in March and April and in the early part of summer, bringing abundant rainfall which is important for transplanting rice. The other type is the typhoon. Typhoons usually originate in the east Philippines, move toward the north and around Taiwan and shift direction mostly northeastward. The most common period for typhoons in Korea is July through August. The southern coast generally gets one or two mild typhoons a year, and a strong one every two or three years.
Seasons
1) Spring
Spring in the Korean Peninsula comes with the arrival of the swallow, a migratory bird from the south, and the blooming of cherry blossoms in the last part of March or early April along the southern coast and nearby islands. It begins in the middle of April in the central part of the country, and in the last part of April in the north. By April, a thaw sets in, and streams swell as ice breaks up, and spring rain comes in drizzles. Rainfall increases gradually during March, April and May. This rainfall is slight, but it is adequate for preparing seedbeds for rice, sowing spring vegetables, and planting summer crops such as barley and soybeans.
Spring winds are characterized by varied direction. The early spring has more gusty and dusty winds from the northwest, and as summer approaches, moist airstreams start blowing from the south. Spring is rather short, usually little more than two months, April and May, especially in the northern part of Korea.
2) Summer
Summer in Korea is hot and rainy. The season usually begins in June, when the temperature rises above 20 degrees C, in most of Korea except the northern interior, and lasts about four months. The monthly rainfall is generally more than 100 millimeters. Summer is the season of cyclonic storms and monsoonal rains. Especially in July there are many rainy days mingled with short clear spells and less cloudy days. Summer rainfall is characterized by heavy showers, often exceeding 200 millimeters of rainfall in a day, or sometimes more than 300 millimeters. This heavy concentration of rainfall occurs frequently in inland basins where airflows converge. During the summer rainy season, rivers and streams throughout Korea are filled with runoff water from the upper reaches which often causes floods. Abundant rainfall and hot summers are necessary for growing rice. Inadequate rainfall or the late arrival of the rainy season is liable to cause failure of rice crops. There is very little difference between north and south in summer temperature. Temperature differences are greater between the coast and the inland areas than between north and south. The highest temperature, 40 degrees C, was recorded at Taegu and the inland basin on August 1, 1942.
3) Autumn
Autumn is rather short, lasting about two months from October to November. This is the season of transition from the hot and wet summer monsoon to the cold and dry winter monsoon. October brings a decided shift in air mass movements with a dry, continental airstream resulting in clear days. Nights are cool, particularly in the north, where frost normally occurs at this time. The clear autumn days are the most pleasant of the year. Dry and sunny weather is indispensable for rice to ripen and for farmers to reap it. In the central and southern parts of Korea, this is the season for planting winter crops such as barley and wheat.
4) Winter
During the winter the climate contrast between the northern and southern regions is most apparent. A January isothermal map shows that the minus 20 degrees C. line passes the northern inland region while the 4 degrees C. line passes the southern coast. Chunggangjin, North Korea, the coldest place on the Korean Peninsula, has a mean temperature of minus 20.8 degrees C. and Chejudo Island has one of 5.2 degrees C. during January, the coldest month. Thus, the north-south difference in January temperatures is about 26 degree C. In the winter of 1933, Chunggangjin had the lowest temperature ever recorded in Korea, minus 43.6 degrees C. Winter is characterized as cold and dry with the cold spell generally caused by the influence of the Siberian high pressure cell, a cold and dry air mass. However, due to fluctuations in the high-pressure cell, the northwest winter monsoon is not continuous, allowing calm periods when the weather is milder. Winter in Korea is long, lasting four months in the central and southern regions. Most rivers in North Korea are frozen over for several months.
The winter temperature has an important bearing on agriculture. Where the cold is not overly severe, two crops, usually rice and barley, may be grown.
Soil
The soil of the lowlands of Korea, as well as the mountain areas, is usually brownish with some variation depending on the bedrock. Most soil is derived from granite and gneiss, with limestone and volcanic rocks in limited areas. Light brown and sandy acidic soils are common in those derived from granite, and clay brown to red soils are common in the granitic gneiss areas. In the areas of Kangwon-do and northern Hwanghae-do provinces, limestone-originated red soils are found. On Cheju-do and Ullungdo islands, and in northern Kangwon-do province, black volcanic soils are common. In the northern mountain areas, podzolic and ash-gray forest soils are found. Cultivated soils, especially paddy soils, are artificial surfaces developed through plowing, irrigation, and fertilizing over long periods. Silt from irrigation water and occasional flooding of rivers has changed the soil composition in many areas to a uniform silty loam unrelated to the natural soils of the vicinity.