Water, Climate, and Vegetation

Earth’s Water Water covers about 70% of the Earth’s surface, most of it is saltwater. Some areas never have enough water to support life while other places get too much. Why?

Climate determines the amount of water a place receives, which also determines its vegetation, or plant life. Water exists in many forms---liquid, vapor or water in the form of gas, glaciers, and ice sheets-- large masses of water in frozen form. The total amount of water on earth does not change.

Climate and Weather Weather Weather refers to the constant changes in the air during short periods of time. Climate Climate refers to the usual pattern of weather events in an area over a long period of time.

The sun’s direct rays fall year-round at low latitudes near the Equator this area known as the tropics lies between the Tropic of Cancer and the Tropic of Capricorn. Outside the tropics the sun is NEVER directly overhead.

Around the poles the sun’s rays hit the earth indirectly at a slant, this causes the temperatures to remain cool or cold even in the midsummer. In addition to latitude, the movement of air and water helps create the Earth’s climates.

– Moving air and water helps circulate the sun’s heat around the globe. – The warmest waters of the world are found near the Equator. – A large, warm-water ocean current known as the Gulf Stream flows from the Gulf of Mexico along the east coast of North America across the Atlantic to Western Europe.

Large bodies of water influence climate because their temperatures do not change as quickly as land temperatures. Storms— moving wind and water make climates milder but they also cause storms. – These storms include hurricanes, typhoons and monsoons.

Climate and Vegetation The world’s climates can be organized into four major regions: tropical, mid-latitude, high latitude, and dry. – There are two types of Tropical Climate: Tropical rainforest climate is wet in most months, with up to 100 inches of rain per year. Tropical savanna climate has a wet season and a dry season.

Mid-Latitude Climates – Are moderated and extend from about 30⁰ N to 60⁰ N of the Equator and 30⁰ S to 60⁰ S of the Equator. – Most of the world’s population lives in this climate. – The mid-latitude climates have a great deal of variety—there are 4 subgroups in this climate.

4 Mid-latitude subgroups Marine West Coast Climate—coastal areas where winds blow in from the ocean, the winters are rainy and mild and the summers are cool. Mediterranean Climate—has mild, rainy winters and hot, dry summers.

4 Mid-latitude climates continued Humid Continental Climate- these are found far from the ocean—winters can be long, cold, and snowy. Summers are short but may be very hot. Humid Subtropical Climate- these are close to the tropics– rain falls throughout the year but is heaviest during the hot and humid summer months, winters are generally short and mild.

High Latitude Climates Range from 60⁰ N to the North Pole and 60⁰ S to the South Pole. – Subarctic Climate- is just below the Arctic Circle. – Very few people live there—they have severely cold and bitter winters. – Temperatures rise above freezing in summer months. – Huge evergreen forests grow here.

Tundra Climate- is harsh and dry. – It is a vast rolling plain without trees – The top few inches of land thaw over summer this makes it possible for sturdy grasses, small berry bushes, and wildflowers to grow. – The lower layers of soil are known as permafrost because they never thaw.

Ice Cap Climate- the polar ice caps and the great ice sheets of Antarctica and Greenland have this bitter cold climate. – Monthly temperatures average below zero. – Only fungus-like plants grow here.

Highland Climate– a highland, or mountainous, climate has cool or cold temperatures year-round. – The elevation, or height above sea level, of a place changes its climate drastically. – Higher into the mountains the air becomes thinner.

Dry Climates Dry Climates-refer to dry or partially dry areas that receive little or no rainfall. – Temperatures can be extremely hot during the day and cold at night – Dry climates can also have severely cold winters. Desert Climate- – These can be found at any latitude – Deserts receive less than 10 inches of rain per year

Steppe Climate – Partly dry grasslands – They get about 10 to 20 inches of rain per year.