Science Key Terms
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61 terms
Terms | Definitions |
|---|---|
 volcano | an opening in the Earth that erupts gases, ash, and lava |
| vent | the opening in a volcano where magma flow out |
| crater | the steep walled depression around a volcano's vent |
| hot spot | unusually hot rock at the boundary between earth's mantle and core is forced toward the crust where it melts to form this |
| shield volcano | quiet eruption of runny and thin basaltic lava flows steadily and builds up in layers that form a broad volcano with sloped sides |
| tephra | bits of rock/solidified lava that is dropped from the air |
| cinder cone volcano | this type of volcano is formed when tephra falls to the ground. It is steep sided and loosely packed. It has a semi explosive eruption |
| composite volcano | this type of volcano forms when the tephra and lave cycle alternate repeatedly. It has tall and steep sides, and it varies between quiet and explosive eruptions |
| divergent boundary | the boundary between two plates that are moving apart |
| atmosphere | layers of gases that surround the earth |
| troposphere | the lowest of earth's atmospheric layers; where weather happens; temperature decreases as you get higher in this layer |
| stratosphere | the 2nd layer of earth's atmosphere; the ozone layer is located here; temperature increases as you get higher in this layer because the ozone layer absorbs heat |
| mesosphere | the layer of the atmosphere where most meteors are burnt up. It is the coldest layer. It is the 3rd from the earth. In this layer, temperature decreases as altitude increases |
| thermosphere | the layer of the atmosphere where the northern lights are. It is the hottest layer because it is closest to the sun. BUT, it would register as freezing on a thermometer because there aren't enough molecules to register on it. The ionosphere is located here. |
| exosphere | the outer layer of our atmosphere |
| ionosphere | a layer of electrically charged particles that allow radio waves to bounce of them and go back to earth. During the day, the sun interferes with the particles in this layer. So, the radio waves only reach earth at night |
| ozone layer | a layer in the atmosphere made of ozone, which has 3 oxygen atoms per molecule. Ozone shields us from the sun's energy and absorbs ultraviolet radiation |
| ultraviolet radiation | one of the many types of energy that come to Earth from the Sun. Too much of this energy can cause skin cancer. The ozone layer helps to absorb some of it. |
| radiation | heat transferred through empty space by rays/waves this is how the sun transfers heat |
| conduction | heat transferred through molecules physically touching each other |
| convection | heat transferred thorough the flow of material (liquids and gases) heated material rises, cools, and then sinks again |
| condensation | when a gas gets cold and the molecules condense, forming a liquid |
| weather | the state of the atmosphere at a specific time and place |
| humidity | the amount of water vapor present in the air |
| relative humidity | a measure of the amount of water vapor present in the air compared to the amount needed for saturation at a specific temperature |
| dew point | the temperature at which air is saturated and condensation forms |
| fog | when air is cooled to its dew point near the ground, it forms a stratus cloud called this |
| air mass | a large body of air that has properties similar to the surface that it formed over |
| front | a boundary between 2 air masses of different density, moisture, or temperature |
| tornado | a violently rotating column of air in contact with the ground |
| stratus cloud | this type of cloud forms very low in the atmosphere. it is usually grey, and covers the sky. When these clouds form close to the ground, they are called fog. They usually bring precipitation. |
| cumulus cloud | white puffy clouds that form when warm air moves up quickly and meets colder air |
| cirrus cloud | a white and wispy cloud that forms very high in the atmosphere. It mostly forms on nice, cool days and can also indicate that a storm is coming |
| axis | the imaginary vertical line around which earth spins. This line cuts directly through the center of earth. The poles are located at the north and south ends of this. |
| rotation | the spinning of earth on its axis, which causes day and night; one of these takes 24 hours |
| revolution | Earth's yearly orbit around the sun; this takes 365 and one fourth days |
| ellipse | an elongated, closed curve; the shape of earth's orbit |
| solstice | the day when the sun reaches its greatest distance north or south from the equator |
| equinox | when the sun is directly above earth's equator |
| moon phases | the different forms that the moon takes in its appearance from earth. the form depends on the relative positions of the moon |
| new moon | when the moon is between earth and the sun. during this, the lighted half of the moon is facing the sun and the dark side faces earth. the moon is in the sky, but cannot be seen |
| waxing | when more of the illuminated half of the moon can be seen each night |
| full moon | when all of the moon's surface facing earth reflects light |
| waning | when you see less of the moon's illuminated half each night |
| solar eclipse | when the moon moves directly between the sun and earth and casts its shadow over part of earth |
| lunar eclipse | when earth's shadow falls on the moon |
| absolute magnitude | a star's true brightness that it would have if it was a standard distance from earth |
| apparent magnitude | a star's brightness as seen from earth |
| light-year | a unit of distance; the distance light travels in one year |
| nebula | a large amount of gas and dust spread out in an immense volume; a baby star |
| giant | the name for a star in its last life stage; the hydrogen in the core gets depleted and the core contracts and heats up while the outer layers of the star expand and cool |
| white dwarf | the stage in a star's life when all that is left is the white, hot, and dense core |
| super giant | when a massive star heats up a lot, the star expands into this |
| black hole | when all of a core's mass collapses to one point and the gravity is so strong that nothing can escape from it, this forms |
| galaxy | a large group of stars, gas, and dust held together by gravity |
| big bang theory | the theory that approximately 13.7 billion years ago, the universe began with and enormous explosion. the entire universe began to expand everywhere at the same time |
| parallax | the apparent change in position of an object when you look at it from different places; astronomers use this to measure distances to nearby stars |
| nuclear fusion | the fusion of 2 hydrogen atoms to make helium. This can only occur under extremely high temperatures and pressure |
| newton's first law of motion | an object at rest will stay at rest and an object in motion will stay in motion at a constant speed and direction unless acted on by an outside force |
| newton's second law of motion | force is equal to a change in momentum, the force of a movement, per change in time. this law explains how the velocity of an object changes when it is acted on by an outside force. An object with more mass will have less acceleration, and the more force you apply to an object, the more acceleration it will have |
| newton's third law of motion | for every action, there is an equal and opposite reaction |
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