Seasons, Weather, and Climate

Unit 1: Basics of Geography

SEASONS

▪ Earth’s Tilt▪ -Seasons affect the conditions in the atmosphere/create our

weather▪ -Because of the earth’s revolution and tilt, different parts of the

earth receive the direct rays of the sun for more hours at certain times in the year. Causes the changing seasons on earth.

▪ Tropic of Cancer and Tropic of Capricorn (latitude lines) mark the points farthest north and south that the sun’s rays directly shine over at noon. The day of which this occurs is called the solstice. In the Northern Hemisphere, the summer solstice (beginning of summer) is the longest day of the year. Winter solstice is the shortest.

▪ - Twice a year, on the equinox, the days and nights all over the world are equal in length. They mark the beginning of spring and fall.

WEATHER

▪ Weather is the condition of the atmosphere at a particular location and time.

▪ Climate is the term for weather conditions at a particular location over a period of time.

WEATHER

▪ What causes the weather?▪ Water vapor-Determines whether or not there

will be precipitation▪ Cloud cover- clouds may hold water vapor▪ Elevation- elevation above sea level increases,

air becomes thinner and loses its ability to hold moisture

▪ Air movement- Winds move the air and moisture it holds

WEATHER

▪ Precipitation▪ -Depends on the amount of water vapor in the air. Warm air rises,

cools, and loses ability to hold water vapor; water vapor condenses, droplets form in clouds. When amount of water is too much for clouds to hold, precipitation falls.

▪ 3 classifications of water vapor1. Convectional-occurs in hot, warm climates2. Orographic- falls on the windward side of

mountains; block moist air and force it upwards; the air cools causing precipitation Land on the leeward side is called rain shadow because it gets little rain.

3. Frontal- More precipitation in the middle latitudes. A front is a boundary between two air masses of different temps.

EXTREME WEATHER

▪ Hurricanes form over warm, tropical water. Aka-typhoons (Asia) Air flowing over 80 degree + water pick up huge amounts of moisture and heat energy. Winds form an eye. Winds around the eye may be as strong as 200 mph. Stretch over a vast area maybe 500 miles wide.

▪ Tornadoes- Form quickly; powerful funnel shaped spiraling air. Born from strong thunderstorms. Winds swirl counterclockwise around a low pressure center. Can reach up to 300 mph. Generally travel small distances. However, can be a mile wide and stay on the ground for hours.

EXTREME WEATHER

▪ Blizzards- Heavy snowstorm with winds more than 35 mph.

▪ Droughts- Long period of time without rain or with very little rainfall.

▪ Floods- Water spreads over land not normally covered with water.

CLIMATE

▪ 4 factors influence the climate of a region▪ 1. Wind and ocean currents▪ 2. Latitude▪ 3. Elevation▪ 4. Topography

CLIMATE

▪ Wind currents-▪ Wind and ocean currents help distribute the

sun’s heat from one part of the world to another through convection- transfer of heat by an upward motion of air.

▪ Wind is caused by air expanding b/c of heat; low air pressure created; cooler dense air in a nearby high pressure zone rushes into the low- pressure area

CLIMATE

▪ Ocean currents- like rivers flowing in the ocean▪ Warm waters flow away from the equator; cold

water towards the equator. ▪ Zones of latitude- Geographers divide the earth

into 3.1. Low or tropical

2.Middle or temperate 3. High or polar

CLIMATE

▪ Tropical zones are on either side of the equator- hot all year long.

▪ Temperate zones lie at the middle latitudes; climates vary from relatively hot to relatively cold

▪ High zones encircle the North and South poles; cold all year long.

▪ Elevation- landforms affect the climate also- mountain areas

CLIMATE

▪ El Nino- the warming of waters off the west coast of S. America. This is a natural change in climate. Happens every 2-7 years. Easterly winds in Pacific change direction or slow- ocean temp changes. It affects the weather worldwide. Heavy rains towards the Americas. Australia and Asia experience drought conditions.

CLIMATE

▪ La Nina- Reverse of El Nino. Winds blow warmer water on the lands of the Pacific rim

▪ Increase in precipitation in India, dryness along the Pacific coast of the Americas

CLIMATE

▪ Global warming- Air temps are increasing ▪ Some believe- natural warming of cooling

cycles▪ Others believe caused by the greenhouse

effect- the layer of gases released by burning coal and petroleum traps some solar energy causing higher temps in the same way a green house traps solar energy

▪ Predict if it continues- ice caps will melt, flooding, covering of islands, changing global climate.

Climate Regions, Soil, Vegetation

Unit 1: Basics of Geography

World Climate Regions□ Geographers must make generalizations

what the typical weather conditions are over many years in a location. They look at precipitation and temperature-Tropical-Dry-Mid latitude-High latitude-Highland

World Climate RegionsThese 5 are divided into small subregions□ Tropical wet- Always hot- avg. temp of 80

degrees; rains daily;more than 80” of rain/yr; Central and South America, Africa, SW Asia

□ Tropical wet and dry- Rainy and warm in summer; dry and cool in winter; Africa, South and Central America, parts of Asia

World Climate Regions□ Semiarid- Receives about 16” of

rain/yr;hot summers, mild to cold winters, some snow; interior of continents or around deserts; good agricultural land

□ Desert- Can be hot or cool/cold; receive less than 10” of rain/yr.

World Climate Regions□ Mediterranean- Around Mediterranean

Sea;west coast of the U.S. and parts of Australia;summers- dry and hot;winters- cool and rainy;rich agricultural activity

□ Marine west coast- Close to the ocean;cloudy, foggy, and damp;west coast of the U.S. and Canada and most of W. Europe;precip evenly distributed thru the year;smog in industrial regions

World Climate Regions□ Humid Subtropical- Summer heat and

humidity; E. coast of continents;subject to hurricanes in late summer and fall; S.E. part of U.S. and large areas of China; winters- mild to cool;grow rice

□ Humid Continental- Great variety in temp/precip;mid latitude interiors of North Hemisphere continent;experience 4 seasons

World Climate Regions□ Sub arctic- Taiga (evergreen

forests);Canada/Russia; summers- short and cool; winters- very cold;temps at freezing or below 5-8 mos/yr

□ Tundra- Flat, treeless ring around the Arctic Ocean- tundra;almost all located in the North Hemisphere;less than 15” of rain/yr;permafrost- subsoil is constantly frozen; summer lasts for a few weeks- temp slightly above 40 degrees

World Climate Regions□ Icecap- Snow, ice, permanent

freezing temps;Polar deserts- Less than 10” of rain/yr

□ Highlands- Climate varies with latitude, elevation

Soil□ Worlds food supply depends greatly on top

6” of soil□ Soil characteristics and climate- major

influences in vegetation regions: depth, texture, and humus content determine vegetation

□ Soil, temp, and moisture determine the type of vegetation in a region

□ Ecosystem- interdependent community of plants and animals

Vegetation□ Biome- ecosystem of a region

-Forest-Grassland-Desert-Tundra

□ Forestlands- Categorized by their trees- broadleaf or needleleaf

-Broadleaf- deciduous- oak, maple, and cottonwood- rainforest covered with these mostly in No. Hemisphere

Vegetation□ Needleleaf-coniferous- pine, fir,

cedar- cone bearing- No. regions of North America, Asia, and Europe

□ Grasslands- Flat regions and few trees

□ Tundra- Mosses and lichens□ Desert-cacti, sagebrush, shrubs

Human-Environment Interaction

□ Human activities on soil and vegetation is immense■ Building dams, irrigation systems,

planting crops, slash and burn