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18 Cards in this Set
- Front
- Back
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Most objects heat up during the day and then radiate IR radiation at night. The ability of an object to store heat is_____ |
Thermal mass |
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What is the daily two part heating and cooling cycle? |
Diurnal cycle |
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A FLIR systems ability to detect temperature differences is referred to as the |
Mean resolvable temperature difference (MRTD) |
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Thin, wispy clouds have greater spaces between particles, therefore a greater amount of the near IR radiation will be passed through without scattering. For this reason, it is possible for the thin, wispy clouds to be invisible to the naked eye, but visible when viewed through NVGs T/F? |
False |
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A lunar month is approximately _____ days? |
29.5 |
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What is the ability of any object to emit thermal energy compared to a black body at the same temperature? |
Emissivity |
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On a moonless night, about 40% of the light is provided by emissions from atoms and molecules in the upper atmosphere known as ______ |
Air glow |
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The AN/AVS-9 NVGS operate in both the ______ and ______ spectrum |
Visible, near IR |
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The time of day and the time of year are the two most prominent factors that dictate the amount of solar radiation available T/F? |
True |
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Surfaces such as snow will reflect less light than surfaces like asphalt or dark rock and therefore will appear lighter in the NVG image T/F? |
False |
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Where do the eye, FLIR, and NVGs fall on the EM spectrum chart |
Eye-0.4-0.7 microns NVGs-0.4-1.2 microns FLIR-3-5 or 8-12 microns |
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What is the point where the background temperature passes or is overcome by the target temperature? |
Diurnal crossover |
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The amount of light provided by the moon is influenced by what four factors? |
1. Lunar cycle 2. Moon angle 3. Lunar albedo (reflectivity) 4. Variation in earth moon distance |
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Define "Delta T" |
Is the concept of temperature difference |
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What are three major factors that influence NVD performance |
Illumination/Thermal scene Terrain contrast Atmospheric conditions |
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What are three principle sources of thermal energy for objects? |
1. Solar radiation 2. Fuel combustion or frictional heat 3. Thermal reflection |
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Frictional heat from moving parts, such as tank tracks, create localized hot spots that tend to form a high contrast spot that AIDS in the detection but could hamper identification efforts T/F |
True |
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________ is a measure of the difference between the reflectivity of two or more surfaces |
Terrain contrast |
