6th Grade Science- Chapter 7 Notes

Chapter 7, Lesson 1 Notes

*A system is a group of parts that work together as a whole.

*The Earth system involves a constant flow of matter through different parts.

*The constant flow, or cycling, of matter through the Earth system is driven by energy.

*Energy is the ability to do work.

*The energy that drives the Earth system has two main sources: heat from the sun and heat flowing out of Earth as it cools

*The Earth system has 5 main spheres: the atmosphere, the hydrosphere, the geosphere, the cryosphere, and the biosphere.

*As a major source of energy for Earth processes, the sun can be considered part of the Earth system as well.

*Earth’s atmosphere is the relatively thin envelope of gases that forms Earth’s outermost layer

*Earth’s geosphere has three main parts: a metal core, a solid middle layer, and a rocky outer layer

*The hydrosphere contains Earth’s water.

*Earth’s cryosphere contains all the water in the form of ice on or in Earth: glaciers, snowfields, ice caps, ice sheets, sea ice, and frozen ground.

*The part of Earth that contains living organisms makes up the biosphere.

Chapter 7, Lesson 2 Notes

*Nearly all of the energy in Earth’s atmosphere comes from the sun and travels as electromagnetic waves, a form of energy that can move through the vacuum of space.

*Electromagnetic waves can be classified according to wavelength.

*Most of the energy from the sun travels to Earth in the form of visible light and infrared radiation.

*A smaller amount arrives as ultraviolet radiation.

*Visible light includes all colors of the rainbow.  The different colors are different wavelengths.

*The direct transfer of energy by electromagnetic waves is called radiation.

*Infrared radiation has wavelengths longer than red light, it’s invisible to humans, but can be felt as heat.

*The sun also gives off ultraviolet radiation, which is an invisible form of energy with wavelengths shorter than violet light.

*Some sunlight is absorbed or reflected by the atmosphere before it can reach the surface, the rest of the sunlight passes through the atmosphere to Earth’s surface.

*Some ultraviolet radiation is absorbed by the ozone layer.  Infrared radiation passes farther before some is absorbed by water vapor and carbon dioxide.

*In the troposphere, clouds reflect some sunlight back into space.

*Earth’s surface radiates some energy back into the atmosphere as infrared radiation.

*Some travels back into space, but much is absorbed by water vapor, carbon dioxide, and other gases.

*These gases hold heat in the atmosphere in a process called the greenhouse effect, which keeps Earth at a comfortable temperature.  Human activities may be altering this process.

*Energy provided by the sun influences global winds and creates temperature differences among Earth’s air, water, and land.

*Global winds are created by the unequal heating of Earth’s surface over a large area.

*Because of Earth’s spherical shape, rays from the sun strike directly at the equator but hit the poles at a lower angle.  As a result, temperatures near the poles are much lower than near the equator.

*The differences between the equator and the two poles produce giant convection currents in the atmosphere.

*Surface winds blow from the poles toward the equator.  Higher in the atmosphere, winds flow from equator to poles.

*The way Earth’s rotations make winds curve is called the Coriolis effect.

*Because of the Coriolis effect, global winds in the Northern Hemisphere gradually turn toward the right.

*Land heats and cools more rapidly than water.

*Also, land can heat to higher temperatures than water can.  

*Land can also cool to lower temperatures than water can.

*Heating and cooling of Earth’s land and water directly affect the air temperature above these surfaces.  This process helps create winds.

Chapter 7, Lesson 3 Notes

*Climate is the typical weather pattern in an area over a long period of time.

*Weather refers to the conditions of Earth’s atmosphere at a particular time and place.

*Climate refers to the average, year-after-year weather patterns in a given area.

*Scientists classify climates according to temperature and precipitation.

*In tropical rainy climates, rainy days and afternoon thunderstorms are common.

*Forests in which large amounts of rain fall year-round are called rain forests and can be found in some tropical rainy climates.  Savannas, or tropical grasslands, are common in these areas.

*Florida is the only place in the United States with a tropical rainy climate.

*A desert is a very dry region with extreme temperatures.

*Only specialized plants can survive there.

*Dry climates on the edge of deserts that are large and semiarid are steppes that generally receive enough rainfall for short grasses and low bushes to grow.

*Climates that are temperate continental are not influences by the oceans and often have extreme temperatures.  Forests and grasslands grow well in these climates.

*Other temperate climates have short cool summer and long, bitterly cold winters.

*Subarctic climates lie north of some continental climates.  Firs and spruce forests often grow in these climates.

*Temperate marine climates are found on the coasts of continents in latitudes just outside the tropics.  Due to the oceans, these climates are humid and have mild winters.

*Humid subtropical climates are warm temperate marine climates, but they are not constantly as hot as the tropics.

*Polar climates are the coldest climate with short, cool summer followed by bitterly cold winters.

*A tundra covers great areas and is a treeless plain beneath which the ground may always be frozen.

*Permafrost is permanently frozen ground.

*Possible natural factors that cause major climate changes include the movement of the continents, changes in the position of Earth relative to the sun, major volcanic eruptions, and changes in the sun’s energy output.

*The movements of continents over time affected the global patterns of winds and ocean currents, which slowly changed climates.

*Over a period of 100,000 years, the shape of Earth’s orbit varies.  When the orbit is more elliptical, less sunlight reaches Earth and causes a cold ice age, a period of glacial advance covering large parts of Earth’s surface.

*Major volcanic eruptions release huge quantities of ash and aerosols, solid particles or liquid drops in gas, into the atmosphere.

*Scientists think aerosols in the upper atmosphere reflect some incoming solar radiation, lowering temperatures on Earth.

*Short-term changes in climate have been linked to changes in the amount of light given off by the sun.

*Scientists use sunspots to measure solar output over the past 400 years.

*The number of sunspots, dark, cooler regions on the surface of the sun, increases when the sun gives off more light.

Chapter 7, Lesson 4 Notes

*A natural disaster is a natural event that causes severe or widespread destruction.

*Natural disasters such as hurricanes, tornados, and wildfires have repeatedly damaged many areas of Florida, causing loss of life and damage to property.

*40% of all hurricanes in the United States hit Florida.

*Much damage can be done by powerful, long-lasting winds sometimes called sustained winds.

*Hurricanes can produce 15-30 centimeters of rain, up to 160 kilometers inland mostly during the 6 hours before and after landfall.  These rains can cause flash floods and mudslides.

*The rush of water that is caused by powerful winds is called a storm surge.  Storm surges are the greatest threat to life and property during a hurricane.

*In the ocean, storm surges can be 80-160 kilometers wide and raise sea levels 4.5 meters above normal tides.

*In the summer months, tornadoes form from tropical cyclones making landfall in Florida.  More powerful tornadoes occur in late winter as the jet stream moves south into Florida bringing strengthened thunderstorms.

*A wildfire is a large fire that spreads quickly over a natural area and is started by lightning, arson, or debris burning.  While wildfires are destructive and dangerous, they also shape the landscape in Florida.

*A flood is an overflowing of water in a normally dry area.

*Hurricanes can bring heavy rains to much of Florida causing flooding.

*Many floods occur when the volume of water in a river increases so much that the river overflows its channel.

*Other floods are caused by storm surges.  Floods can be caused by storm surges from ocean or from large lakes.

*People try to control floods by building dams.

*A long period of scarce rainfall or dry weather is known as a drought.  Droughts are usually caused by dry weather systems that remain in one place for weeks or months at a time.

*Long-term droughts can cause crop failure and even famine.  People can prepare by conserving water when dry conditions first occur.

*If you hear a hurricane warning and are told to evacuate, leave the area immediately.

*The safest place to be during a tornado is in either a storm shelter or a basement.

*During thunderstorms, avoid places where lightning may strike.  Also, avoid objects that can conduct electricity, such as metal objects and bodies of water.

*The sun can be harmful to your skin and eyes.  To protect yourself from the harmful effects of the sun’s ultraviolet radiation, limit your exposure to the sun.

*If you are outside for a duration of time, apply sunscreen with UVA/UVB protection, wear clothes and wear sunglasses.  Clouds do not block sun’s harmful ultraviolet radiation.