South Korea is located on the southern portion of the Korean Peninsula. Borders North Korea with 238 km along the Korean Demilitarized Zone. Has 2,413 km coastline along three seas: Yellow, East China, and Sea of Japan. Total land area is 100,364 square kilometers, 290 square kilometers water
Kathmandu is Nepal's capital and most populous city with 845,767 inhabitants (2021). Located in Kathmandu Valley at 1,324 meters above sea level. City covers 50.7 km² and is divided into 32 administrative wards
Acid rain has pH below 5, typically ranging from 4-5. Main causes are sulfur dioxide and nitrogen oxide emissions from human activities. Natural sources include volcanic eruptions and lightning strikes
Contrails are line-shaped clouds produced by aircraft engine exhaust. Primarily composed of water in ice crystal form. Form at high altitudes above 8,000m with temperatures below -36.5°C. Can persist for hours and spread to several kilometers wide
Smog is intense air pollution combining smoke and fog. Term coined by Henry Antoine Des Voeux in 1905 for London's "pea soup fog". Composed of nitrogen oxides, sulfur oxide, ozone, smoke and particulates
AQI indicates current or forecasted air pollution levels. Government agencies develop AQI to communicate air quality to public. Children, elderly and those with health problems are first affected