Physical Geography Lesson 1 Planet Earth Earth is

Physical Geography Lesson 1: Planet Earth

• Earth is one planet among a group of planets and other bodies that revolve, or orbit, the sun and make up the solar system. • Earth rotates on its axis. One rotation takes 24 hours. As Earth rotates, some areas are in sunlight (day), and others are in darkness (night).

• Earth is made up of three layers: the core, the mantle, and the crust. There is a solid inner core and an outer core of melted, liquid metal. In the mantle layer, a thick layer of magma surrounds the core. The crust, Earth’s rocky outer shell, ranges in thickness from 2 miles (3. 2 km) under oceans to about 75 miles (121 km) under mountains. • Earth’s four physical systems are the hydrosphere (water), the lithosphere (crust), the atmosphere (gases that envelop Earth), and the biosphere (all living things).

• Because Earth’s axis is tilted as it orbits the sun, the sun’s direct rays reach different parts of the globe at different times of the year, which causes seasons. • On or about June 21, summer begins in the Northern Hemisphere and winter begins in the Southern Hemisphere. • On or about December 22, summer begins in the Southern Hemisphere and winter begins in the Northern Hemisphere.

Climate • Climate around the world is different depending on where you are and when you are there. • No two places on Earth are exactly alike, therefore no two places share the same climate. • However, there are similar climate types all round the world. • The Koppen climate classification system allows us to classify world climates into groups. It divides the world’s climates into four main types.

• Climate describes the average weather conditions in an area over a long period of time. • Weather refers to conditions in the atmosphere at any given time.

• Elevation, wind and ocean currents, weather, and landforms affect climate. • Earth is divided into climate zones based on temperature, precipitation, distance from the equator, and elevation.

• Many scientists say the world’s climates are changing. • Some of this change may be due to human activity. • Scientists have noticed global warming, an increase in the average temperature of Earth’s atmosphere.

The climate zones are: tropical, desert, humid temperate, cold temperate, polar, and high mountain. Foldable

Tropical Climate • Type A • Mostly located in a ring around the middle of the globe. • Lie between latitude 15°N and 15°S. • Known for being warm all year round. • Average temperatures do not fall below 64°F • Many are tropical rain forests. • Many receive over 100 inches of rain a year. • Have two seasons wet and dry. • They are frost free which means they have a year round growing season. • The rain forests of Central and South America are good examples.

Humid Temperate • Type C: • One of the most common climates around the world. • Located in the lower parts of the northern continents. • Between 25°-75°N and 25°-75°S latitude. • Has four seasons, but winter is not that cold. • Average temperature of 56°F • Gets about 32 inches of rain per year • Tends to be influenced by ocean currents. • Spain, Alabama, South Carolina are all examples of this climate.

Polar • Type E • Found mostly above or below latitude 60°N or S. • The North Pole and Antarctica cover most of the polar region. • They are cold all year long. • Temperatures do not exceed 50°F. • Get NO precipitation only snow. • Covers 20% of the planet • Receives 6 months of daylight and 6 months of night. • The extreme temperatures result in tundra, glaciers, or permafrost (always frozen ground) • Cool summers, Cold Winters • Alaska and parts of Canada are examples of this climate.

Desert • Type B • Dry and Arid • Found mostly between latitude 50°N and 50°S • Usually hot and sunny • Water evaporates quickly in this climate and rarely falls as precipitation. • Not enough water to maintain most vegetation. • Tends to be filled with scrub bush • Highs can reach 122°F or higher in the deep desert during the day • Can reach below freezing at night • We are an example of this climate.

Cold Temperate • Type D • Also called continental climate • Must have 30 days of snow on the ground a year. • Hot summers and cold winters • Has four seasons • Occurs more in the Northern Hemisphere • Precipitation tends to occur in summer between 24 and 47 inches per year • Tends to be forested. • Between 25°-75°N and 25°-75°S • Continental winters are colder than temperate winters.

High Mountain • Type B • Very little precipitation. • This is also called the Cold Desert • Scotland mountain tops are Climate. examples of this climate • Very little vegetation • Too high for trees to grow • Also referred to as Highland Climate because it occurs above a certain elevation.