(Encyclopedia) myasthenia gravismyasthenia gravismīəsthēˈnēə gräˈvĭs [key], chronic disorder of the muscles characterized by weakness and a tendency to tire easily. It is caused by an autoimmune…
(Encyclopedia) heartburn, burning sensation beneath the breastbone, also called pyrosis. Heartburn does not indicate heart malfunction but results from nervous tension or overindulgence in food or…
(Encyclopedia) sleep apnea, episodes of interrupted breathing during sleep. Obstructive sleep apnea is a common disorder in which relaxation of muscles in the throat repeatedly close off the airway…
(Encyclopedia) whale shark, large, plankton-eating shark, Rhincodon typus, found in all tropical seas of the world. Whale sharks are the largest fish in the world. A female typically reaches about 46…
HOW DO GLACIERS FORM? WHAT ARE ICE CAPS? ICEBERG FIND OUT MOREAt the poles and on high mountains, vast areas are covered in ice—in rivers of ice called glaciers, and in layers of ice called ice…
Galveston Storm SurgeWeatherBlowing Cold and Hot: The Big OnesWinter Gone SouthBig-City SnowsStorm of the Century?The Greatest One of AllModern Winter of Deep SnowsGalveston Storm SurgeThe Great New…
(Encyclopedia) Kootenay National Park, 543 sq mi (1,406 sq km), SE British Columbia, Canada; est. 1920. In the Rocky Mts. near Kootenay Lake, it contains high peaks, glaciers, deep canyons, and hot…
(Encyclopedia) Sigsbee, Charles Dwight, 1845–1923, American naval officer, b. Albany, N.Y. He saw service in the Gulf of Mexico in the Civil War, was subsequently stationed with the Asian squadron,…
(Encyclopedia) Zion National Park, 146,592 acres (59,349 hectares), SW Utah. First proclaimed a national monument in 1909, it was enlarged several times and established as a national park in 1919.…
MIGRATING REINDEERLONG JOURNEY HOMELONG-DISTANCE NAVIGATIONMONARCH MARATHONDORMANCYFIND OUT MOREAnimals have many instinctive behaviours that are linked to climate. Seasonal changes trigger…
