Chapter 2 Summary
Land, water, air, climate and weather make up the physical geography of Earth. Earth rotates all the way around once a day on its tilted axis. This causes day as it turns toward the sun and night as it turns away from the sun. Earth orbits around the sun. It takes one entire year to orbit completely around the sun. The tilt of Earth's axis causes changes in temperatures and lengths of day and night. Seasons are caused by the temperature changes.
Some scientists believe that 200 million years ago Earth had a huge landmass or "supercontinent," which scientists named Pangaea. Pangaea broke apart over the course of millions of years forming the continents we are familiar with today. A theory called plate tectonics explains why Pangaea broke apart. Tectonic plates, which are gigantic pieces of land, float on the magma below them. This changes Earth's surface and causes the land masses to move. Earthquakes and volcanoes can be caused by the land masses colliding or rubbing against each other.
Landforms on Earth can be slowly broken down by the processes of weathering and erosion. After landforms are broken down, erosion carries the small pieces of broken down land to different places, creating new landforms. Weathering and erosion are both caused by wind, rain and ice.
The atmosphere is a layer of gases that surround Earth. Some of these gases, such as oxygen and carbon dioxide are used by plants and animals to survive. Another thing the atmosphere does is trap heat and keep Earth warm.
We call day to day changes in air temperature and precipitation (rain, snow, etc.) weather. Weather patterns observed over long periods of time is called climate. Many things can affect an area's climate, including elevation (how high above sea level an area is - mountains have a high elevation), wind and ocean currents, and where on Earth's latitude range an area lies. Equatorial areas are hot - remember the equator is a line of latitude. Another line of latitude is the arctic circle. The climate is cold there. There are 5 general types of climate: dry, moderate, tropical, polar and continental. Each climate has it's own type of vegetation, weather and seasons.
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