Pages 26-41

Ch. 2 Section 1: Earth and The Sun’s Energy Rotation Earth’s Rotation Earth spins on its axis—an imaginary line that runs through the center of the planet around which it turns. It takes Earth 24 hours to make one rotation, or complete spin on its axis. As Earth spins, different parts of the planet face the sun, thus causing the changes from day to night. Earth’s rotation creates a sense that the sun moves from east to west.

Ch. 2 Section 1: Earth and The Sun’s Energy Revolution Earth’s Revolution Earth follows an orbit, or path, around the sun. It takes Earth 365¼ days to complete one revolution, or trip around the sun. February 29, leap year, is added every four years to allow for the fraction of a day of the revolution. Revolution effects the amount of solar energy that the planet receives.

Ch. 2 Section 1: Earth and The Sun’s Energy Tilt Latitude Earth’s axis is tilted at an angle of 23½ degrees from vertical. Places tilting toward the sun receive more solar energy and have warmer temperatures than those that tilt away. Tilt creates Earth’s change in seasons. Latitude is the distance north or south of Earth’s equator. Low-latitude areas, those nearest the equator, receive direct rays from the sun all year. High-latitude areas, those farther from the equator, receive indirect rays from the sun and have colder temperatures. Areas near the Arctic and Antarctic circles can receive up to 24 hours of sunlight a day.

Ch. 2 Section 1: Earth and The Sun’s Energy (The Seasons) Winter and Summer Spring and Fall Earth tilts away from sun in winter and towards the sun in summer. Because of the Earth’s tilt, the Northern and Southern hemispheres experience opposite seasons (Ex: When it is summer in the Southern Hemisphere, it is winter in the Northern Hemisphere) In spring, Earth begins to tilt toward sun, solar energy increases, temperatures rise, and days grow longer. In fall, the opposite occurs.

Ch. 2 Section 1: Earth and The Sun’s Energy (The Seasons) In the tropics, regions close to the equator, seasons are marked by rainfall rather than temperature. At certain times of year, seasonal winds called monsoons bring either dry or moist air to the tropics, creating wet and dry seasons.

Ch. 2 Section 1: Earth and The Sun’s Energy (The Seasons)

Ch.2 Section 2: Water on Earth Freshwater Salt Water Freshwater makes up only 3 percent of our water supply. Much of Earth’s freshwater is locked in glaciers in the ice of the Arctic and Antarctic regions. Surface water, less than 1% of the freshwater supply, is found in Earth’s streams, rivers, and lakes. Precipitation is water that falls to Earth’s surface as rain, snow, sleet, or hail. Most available freshwater is groundwater, water underground. About 97 percent of the Earth’s water Unsafe to drink because of high levels of salt In general, found in Earth’s oceans, which cover some 71 percent of the planet’s surface Also found in some of Earth’s lakes

Ch.2 Section 2: Water on Earth Water Cycle Water Cycle in Action Water is the only substance on Earth that occurs naturally as a solid, a liquid, and a gas, or water vapor. The water cycle is the movement of water from Earth’s surface to the atmosphere and back ; it is driven by the sun’s energy. The main processes of the water cycle are evaporation, condensation, precipitation, and runoff.

Ch.2 Section 2: Water on Earth Water Problems Water Benefits Shortages of freshwater can be caused by drought. Contaminated, or polluted, water can harm humans, plants, and animals. Flooding can damage property and threaten lives. Provides us with food to eat Important source of energy Provides us with recreation, including swimming, fishing, surfing, and sailing

Ch.2 Section 3: The Land Landforms, or shapes on the planet’s surface, make up the landscapes that surround us. Earth’s landforms include mountains, valleys, and peninsulas.

Ch.2 Section 3: The Land The Earth’s Layers The Earth’s Layers (cross- section) Crust: the solid outer layer of the Earth. Mantle: the Earth’s liquid layer. Core : the solid inner layer of the Earth.

Ch.2 Section 3: The Land Earth’s Plates Movement of Continents The planet’s continents, or large landmasses, are part of Earth’s crust—the solid outer layer of the planet. Theory of plate tectonics suggests that Earth’s surface is divided into a dozen or so slow-moving plates, or pieces of Earth’s crust. Continental drift, a theory developed by Alfred Wegener, states that the continents were once united in a single supercontinent and over time, slowly separated and moved to their present positions. Continental drift As plates collide, separate, and slide, they shape Earth’s landforms.

Ch.2 Section 3: The Land Plate’s Collide Plate’s Separate Two ocean plates: one pushes under the other, creating ocean trenches, or deep valleys in ocean floor Ocean and continental plate: ocean plate drops beneath continental plate, forcing land above to crumple and form mountain range Two continental plates: land pushes up to form mountains. As plates move apart, gaps between plates allows lava to rise and forms a mid- ocean ridge.

Ch.2 Section 3: The Land Weathering Erosion Weathering is the process by which rock is broken down into smaller pieces called sediment. Heating and cooling can cause rocks to crack. Expansion of water as it freezes can cause cracks to expand. Roots of trees can pry rocks apart. Erosion is the movement of sediment from one location to another. Wind Erosion: Winds lift sediment into air and carry it across great distances. Glacial Erosion: Glaciers crush rock into sediment and move it great distances. Water Erosion: Waves and flowing water can cut through rock, carry sediment, and deposit sediment in new locations.