Term
| What is the Stefan-Boltzmann Law? |
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Definition
| By the formula E=σT4, a principle demonstrating that an increase in an object's temperature exponentially increases its radiation emissions |
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Term
| What is Wien's Displacement Law? |
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Definition
| By the formula λmax ≈ 3000/T µm, the wavelength at which an object emits most of its radiation depends upon its temperature |
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Term
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Definition
| An object which is both a perfect absorber and emitter of all radiation (e.g. the sun or Earth) |
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Term
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Definition
| A principle which states that an object which absorbs radiation of a certain wavelength efficiently emits that radiation equally well |
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Term
| What do all electromagnetic waves have in common? |
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Definition
| They all move at the same speed |
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Term
| Do the wavelength and frequency of radiation play into its energy output? |
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Definition
| Yes: long wavelength radiation carries low energy and short wavelength radiation carries high energy, while high frequency radiation carries high energy and low frequency radiation carries low energy |
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Term
| Which have the longer wavelength, ultraviolet light waves or infrared light waves? |
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Definition
| Ultraviolet light waves have a shorter wavelength (≤0.4 μm), and infrared light waves have a longer wavelength (≥0.7 μm) |
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Term
| What is radiative equilibrium, and by extension, radiative equilibrium temperature? |
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Definition
| Radiative equilibrium is a state in which a body absorbs as much radiation as it emits, and radiative equilibrium temperature is the temperature of the surface of a body at which it reaches that state |
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Term
| What is a selective absorber? |
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Definition
| In contrast with black bodies, these are objects that absorb some types of radiation while allowing others to pass through them (e.g. the atmosphere) |
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Term
| What is an atmospheric window? |
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Definition
| A group of wavelengths of radiation that are not absorbed or emitted by our atmosphere |
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Term
| What are three examples of atmospheric gases that absorb radiation better than others, also known as greenhouse gases? |
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Definition
| Water vapor (H2O), carbon dioxide (CO2), and methane (CH4) |
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Term
| Why is the surface temperature of a planet with an atmosphere higher than that of a planet without? |
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Definition
| The atmosphere absorbs incoming radiation and outgoing radiation |
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Term
| How does water vapor play into a positive feedback system? |
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Definition
| With more CO2, an atmosphere absorbs more radiation and thus heat, increasing its water vapor capacity; the water vapor is then able to absorb additional radiation, warming the atmosphere further |
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Term
| What is the angle of incidence? |
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Definition
| The angle at which the sun's radiation strikes Earth's surface |
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Term
| When is the angle of incidence higher, at noon or at dusk/dawn? |
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Definition
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Term
| What is the plane of the ecliptic? |
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Definition
| The horizontal plane upon which Earth completes its revolution |
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Term
| When, approximately, are the Summer and Winter Solstices in the northern hemisphere? |
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Definition
| June 22 and December 22, respectively |
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Term
| What is the cause of the seasonal temperature lags of Earth's climate? |
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Definition
| The temperature is largely controlled by the temperature of the oceans; and water, having a high specific heat, takes a long time to increase or decrease in temperature |
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Term
| How is heat redistributed across the planet, between tropical and polar regions? |
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Definition
30% latent heat: excess tropical energy is invested in evaporating water, which is then sent poleward by wind currents; the vapor condenses in the poles, releasing heat back into the environment
40% midlatitude cyclones: these storms send warm air to the poles from the tropics, and cold air to the tropics from the poles
30% ocean currents: water moves between the poles and the tropics, gaining or losing only some heat along the way because of its high specific heat |
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Term
| Why is there a lag in daily temperature change? |
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Definition
| Though Earth emits infrared radiation at a more or less constant rate, it absorbs solar radiation with the presence of the sun; as the sun rises in the sky, Earth's surface absorbs increasingly more radiation, until the incoming energy finally equals and then exceeds the outgoing energy—it is then that the Earth's surface stops losing heat and starts regaining heat; the converse is true for sunset |
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Term
| What factors may lengthen or shorten daily temperature lag? |
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Definition
| Early cloud formation: radiation trapped and blocked, max temperature reached earlier; large body of water: afternoon breezes cool air down, max temperature reached earlier; storms: disruption by currents, max temperature at any time; surface wetness: energy required to evaporate moisture, max temperature reached later; humidity/haze: radiation partially blocked, max temperature reached later |
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Term
| What is radiation inversion? |
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Definition
| The effect of the ground cooling faster than the air above it, resulting in the lowest temperatures found near the ground, usually around dawn; snow on the ground increases this effect, as it absorbs and emits IR radiation efficiently |
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Term
| Name three factors that may lead to varied temperature at a given latitude |
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Definition
| Proximity to water, ocean currents, and elevation |
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Term
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Definition
| The deflection of a wave of electromagnetic radiation off an object at the same angle of incidence at which it originally struck the object |
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Term
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Definition
| The deflection of a wave of electromagnetic radiation off an object at any angle |
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Term
| Does an object absorb any radiation upon scattering it? |
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Definition
| No; the energy is preserved and re-sent into its surroundings |
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Term
| Why do clouds appear white? And why do thicker clouds appear grey or even black? |
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Definition
| Cloud droplets with a radius of 20 µm scatter all waves of visible light equally; in thicker clouds, light is scattered out the sides before it can reach the bottom |
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Term
| Which wavelengths of light are scattered best by our atmosphere and why? What does this have to do with the color of the sky? |
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Definition
| Our atmosphere scatters short wavelengths best, as they have more potential points of contact with air molecules; the sky is blue because blue light has short wavelengths, and because our eyes are most sensitive to blue light |
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Term
| Why does a hazy sky sometimes appear white? |
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Definition
| On particularly humid days, water droplets suspended in mid-air can reach 20 µm, at which point they scatter all visible light like cloud droplets |
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Term
| Why does the sky appear red during sunset and sunrise? |
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Definition
| Because of the low angle of indicence of sunlight, the light has more air molecules to travel through, and so longwave radiation has the easiest time bypassing the air without being scattered |
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Term
| Is the speed of light always the same? |
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Definition
| No; waves of electromagnetic radiation travel at different speeds through different media |
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Term
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Definition
| The bending of an electromagnetic wave as it passes at an angle from a medium of a certain density to one of a different density, and thus changes in speed and angle |
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Term
| What is the hydrologic cycle? |
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Definition
| The movement and concurrent transition of water from liquid to vapor, and then from vapor back to liquid or to a solid; water remains in a gaseous state for approximately nine days |
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Term
| What will happen if an open container of water is placed in a room with air unsaturated with water? Saturated with water? |
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Definition
| Unsaturated: more water will evaporate into the air than will condense back into the container; saturated: equal amounts of water will evaporate into the air as will condense back into the water |
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Term
| At what temperature is air able to hold more moisture (i.e. harder to saturate)? |
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Definition
| Air holds more moisture and is harder to saturate at higher temperatures |
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Term
| What are the two ways of increasing the saturation of a parcel of air? |
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Definition
| Adding water vapor to the air or cooling the temperature of the air |
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Term
| What is absolute humidity? Why is it not typically used? |
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Definition
| A measure of the mass of water vapor in a given volume of air in g/m3; it is not used due to gases' variable volume |
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Term
| What is specific humidity? Why is it not as valuable as a mixing ratio? |
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Definition
| The mass of water vapor within a parcel of air in g/kg; the total mass of air changes if some of the water vapor condenses, and so the specific humidity does not reflect true changes in water content |
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Term
| What is the mixing ratio? |
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Definition
| The mass of water vapor within a parcel of air divided by the mass of the dry air containing it (g/kg) |
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Term
| What is the saturation mixing ratio? |
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Definition
| The mass of water vapor in a saturated parcel divided by the mass of the dry air that contains it |
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Term
| What is partial pressure? |
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Definition
| The portion contributed by a specific gas to the total pressure of a gaseous mixture |
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Term
| What is vapor pressure? How is it useful in observations? |
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Definition
| The contribution of water vapor to the total pressure of a mixture of air; it may be used to measure humidity, as the mass of the water vapor factors into its vapor pressure |
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Term
| What is saturation vapor pressure? How is it deduced? |
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Definition
| Saturation vapor pressure is the vapor pressure produced by the water vapor in a saturated parcel of air; it can be measured through the temperature of the parcel |
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Term
| What is relative humidity (RH)? |
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Definition
| The mixing ratio divided by the saturation mixing ratio, or the vapor pressure divided by the saturation vapor pressure, expressed as a percentage |
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Term
| What are the two ways of changing the relative humidity of a sample of air? |
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Definition
| Changing the amount of water vapor in the sample or changing the temperature of the sample |
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Term
| What is the dewpoint temperature? |
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Definition
| The temperature to which a sample must be cooled at constant pressure in order to reach saturation |
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Term
| How does the difference between the current temperature and the dewpoint temperature relate to relative humidity? |
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Definition
| A high difference means low relative humidity, and a low difference means high relative humidity |
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Term
| What is the wetbulb temperature? |
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Definition
| The temperature to which air is cooled by evaporating water into it until it is saturated |
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