Lecture – 8 geography of the usa

5. Climate
Most of the United States has a continental climate, characterized by considerable annual variability. Coastal regions, moderated by the oceans, have less variable climates; Hawaii has slight variability, with most of the variation due to elevation. Alaska is partly cold-wet and partly cold-dry. Much of the northern half of the states is permanently frozen, in places to depths as great as 300m.
The eastern United States is humid, with annual precipitation averaging more than 500mm. the western part of the country- beginning approximately at 100 degrees west longitude-expect for the mountains and the maritime Pacific coast, is mostly semiarid with annual precipitation averaging between 250 and 500mm, but parts are arid with annual precipitation averaging less than 250mm. the western mountains received about 500mm of precipitation yearly. The northwestern coast receives more than 2,500mm of precipitation each year.
A traverse eastward across the United States illustrates the importance of seasonal differences in precipitation. Along the Pacific coast precipitation occurs mostly during the winter. In the central United States it is greatest during the summer growing season, further contributing (along with the rich soils) to the agricultural productivity of that region. In eastern states precipitation is rather even throughout the year. The traverse also shows that precipitation is greatest at the mountains and least to the leeward of them.
The country’s temperatures are as varied as precipitation and are heavily influenced by latitude; with longer and colder winters farther north. Temperatures are also influenced by proximity to the oceans. In the northeastern part of the country the average annual temperature in New York is 13 degrees C. Farther south is a subtropical zone: Charleston, S.C has an average annual temperature of 19 degrees C. The only tropical zone of the United States occurs in southern Florida, and Miami experiences an average temperature of 24 degrees C. In the central United States the continental climate is not moderated by the ocean, and seasonal differences are more extreme. In Minneapolis, Minn., the average temperature is 7 degrees C, whereas in Tulsa, Okla ., only about 2 degrees farther west but 1,030km south, the temperature averages 16 degrees C. Along the west coast, temperatures, moderates by the ocean, are mild. Portland, Oreg., has an average annual temperature of 12 degrees C; Los Angeles, in the Mediterranean climate zone, experiences a temperature of 17 degrees C.
Climate hazards in the United States include hurricanes along the Gulf and Atlantic coast, tornadoes in the southeast and central states; hail on the western plains, dry electric storms that cause forest fires on western mountains, floods in the central and eastern states and along the Pacific coast in winter, and droughts in most of the western states.
European place names appeared in America beginning with the 16^lh century, then Europeans came to inhabit the New World. The names were brought by the new inhabitants, who moved from the East Coast to the west, as more and more people arrived from European Some of the names that appeared on the map at that time were those of English and French kings and queens. Many place names were taken from history and literature. There were names taken from geology, others were contested with important events in the life of the people. Here and there, we find a name that was given simply as a joke, but for some reason was never changed¹.
The first people to arrive in America from Holland built a town which they named New Amsterdam, in honour of the capital of their county in Europe. But forty years later, when Holland was at war with England, English fleet under the command of the Duke of York appeared before New Amsterdam. The town had to army; the English occupied the town and renamed it New York. And this, as we know, is the name that has remained to this day.