8th Grade Natural Disasters and Human Impact Study Guide 1. Where’s is most of Earth’s water located? In the oceans 2. What are meterologists? Scientists who study the atmosphere and weather 3. What are droughts? A prolonged period of abnormally low rainfall, resulting in drying out of plant life and can contribute to wildfires 4. What are tornados? A violently rotating column of air that is in contact with the ground 5. Where do climate conditions cause hurricanes to become larger and more powerful? Over warm water 6. What contributes to the formation of hurricanes during the late summer? The interaction between ocean water temperatures and warm air masses 7. What happens to the water when fertilizer runs off into a lake or pond? Eutrophicationovergrowth of algae in the lake or pond, resulting in death of underwater plants, decomposition of those dead plants by bacteria, leading to lack of oxygen in the water and death of aquatic life (such as fish) 8. Where does water vapor come from in the atmosphere? Mostly from evaporation of surface water 9. ¾ of Earth’s surface is covered by water. Describe nearly 97% of the water on Earth’s surface? It is saltwater. 10. Where is most of Earth’s freshwater? Frozen in the polar ice caps and glaciers 11. Which technology best monitors temperature changes in Earth’s ocean? Satellites 12. Humans throughout the world compete with other organisms for water resources. Why would restricting irrigation be a good way to manage water resources and allow all components of the environment to share them? It allows us to conserve water so that there will be enough freshwater for humans as well as other animals and plants in the environment. 13. Why are industrial factors a major source of air pollution created by humans? Because the burning of fossil fuels by industry (such as factories and vehicles) results in the production of poison gases and particulate matter that are the major kinds of air pollution 14. What is an earthquake? What piece of technology is used to measure earthquakes? The shaking and trembling that results from movement of rock (plates) beneath Earth’s surface 15. Why would an uplifted mountain be a feature most likely formed at converging continental tectonic plate boundaries? Because the two continental plates are of similar density, neither plate subducts. Instead, the crust just piles up and forms mountains. 16. Why would a volcanic island arc be a landform most likely created when two oceanic plates converge? Because one of the oceanic plates will subduct under the other and melt to form magma. This magma will then erupt onto the ocean floor. This magma builds up n the ocean floor over time, until it rises above the water, forming a volcanic island. There are usually many of these islands formed as chains and so they are called island arcs. 17. What evidence do we have that the Earth’s continents were once in vastly different positions than they are today? Evidence such as fossils of the same species being found on two totally different continents with different climates oceans apart. 18. Why is sea-floor spreading evidence of plate tectonics? Because the fact that the sea floor is getting wider as it spreads is evidence that the plates must be moving apart, allowing magma to reach the surface of the sea floor and form new sea floor, which is what causes the sea floor spreading to occur 19. What does the Richter scale measure in regards to earthquake characteristics ( energy, magnitude, frequency, or probability)? Energy and magnitude 20. What causes the movement of Earth’s tectonic plates (think about the layers of the Earth)? Convection currents in the mantle 21. What are convection currents? Where do they occur? Hot magma at the bottom of the mantle rises because it is less dense. It cools when it gets to the top of the mantle and falls again because it becomes denser when it gets cooler. This creates circular currents that are like liquid “wheels” that move the tectonic plates. These currents occur in the mantle, specifically the middle mantle, also called the asthenosphere. 22. Earthquake waves are recorded by seismometers. What does an earthquake wave transmit that is recorded by the seisometer? Energy 23. Two plates composed of rock that has similar density meet along a convergent boundary. What will happen where the two plates meet? Because they have similar density, neither will subduct. Instead, the crust will fold and pile up, forming mountains. 24. What happens at the mid-ocean ridge? Oceanic plates are diverging, or pulling apart, which allowing magma to rise to the ocean floor, where it hardens and forms underwater mountains called the mid-ocean ridge 25. How do earthquakes tell scientists about the history of the planet? They tell us that the Earth’s lithospheric plates are constantly moving 26. What are Earth’s five spheres? Hydrosphere (frozen part called cryosphere), geosphere, biosphere, atmosphere 27. What is included in the Atmosphere? Biosphere? Geosphere? Hydrosphere? Cryosphere? Atmosphere-air, wind, lightning Biosphere- all living things including plants, animals, fungi, as well as organic matter that has not yet decomposed Geosphere- rocks, soil, minerals, all of earth’s layers from core to crust, magma 28. Which scale is used to determine the strength of a tornado? Fujita scale 29. Which two elements primarily make up the atmosphere? Nitrogen (78%) and oxygen (21%) 30. What happens to the Earth’s pressure and temperature as you move from the crust to the core? As you move from crust to core, the pressure and temperature increase. 31. What is Pangea? Supercontinent that existed long ago in which all continents were together as one big land mass 32. What is subduction? When an ocean plate (more dense) converges with a continental plate (less dense). The ocean plate goes under the continental plate and melts and turns back into magma. 33. Why do earthquakes occur more frequently in California than Kentucky? Because there is an active fault line in California and there is not one in Kentucky. Slipping and sliding of crustal paltes along this transform boundary is what causes the earthquakes that occur so frequently in California. 34. How do natural disasters interact with Earth’s spheres? Natural disasters can affect all four of Earths spheres. They can cause flooding and fires, which affect the hydrosphere, geosphere, and atmosphere. They can kill people and animals and plants, which affects the biosphere. Natural disasters such as volcanoes and earthquakes are part of the geosphere. Natural disasters such as tornadoes and hurricanes, lightning, and thunderstorms are part of the atmosphere. Flooding and hurricanes are part of the hydrosphere that can affect the geosphere and biosphere. The list and discussion could go on and on.