| A | B |
|---|
| atmosphere | The gaseous envelope surrounding the earth. |
| troposphere | The first layer above the surface and contains half of the Earth's The first layer above the surface and contains half of the Earth's The first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer. |
| stratosphere | The region of the upper atmosphere characterized by little change in temperature as you go up. |
| mesosphere | The portion of the atmosphere above the earth's surface, characterized by temperatures that decrease as you go up. |
| thermosphere | The region of the upper atmosphere in which temperature increase as you go up. |
| ionosphere | Part of the thermosphere but very important. This area makes long distance radio communication possible by reflecting radio waves back to Earth. |
| exosphere | Where the atmosphere merges into space. This is the upper limit of our atmosphere and extremely thin. |
| ozone layer | A region of the upper atmosphere containing a high concentration of ozone that absorbs solar radiation. |
| meteorology | the science dealing with the atmosphere and its phenomena, including weather and climate. |
| aurora borealis | a display of colored lights in the sky, also called northern lights, caused by the interaction of particles from the sun with the upper atmosphere. |
| core | The central portion of the earth, believed to be composed mainly of iron & nickel in a molten state. |
| mantle | The portion of the earth, between the crust and core. |
| crust | The outer layer of the earth, about 22 miles deep under the continents and 6 miles deep under the oceans. |
| sedimentary rock | Rock that has been formed through the deposition & solidification of sediment. These are often deposited in layers, and frequently contain fossils. |
| igneous rock | Rock formed by the solidification of molten magma. |
| metamorphic rock | Rock that was once one form of rock but has changed to another under the influence of heat and/or pressure. |
| weathering | Various mechanical and chemical processes that cause exposed rock to decompose. |
| stalactite | A deposit, usually of calcium carbonate, shaped like an icicle, hanging from the roof of a cave. |
| stalagmite | A deposit, usually of calcium carbonate, resembling an inverted stalactite, formed on the floor of a cave. |
| geology | The science that deals with the dynamics and physical history of the earth. |
