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17 Cards in this Set
- Front
- Back
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Troposphere |
The lowest layer of the atmosphere near the earth's surface extending to altitudes of 12 to 20km |
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Troposphere characteristics |
1. A rate of temperature decrease with height of 6°C/km 2. A decrease of temperature horizontally towards the poles. 3. The presence of horizontal and vertical winds. 4. Most amount of water vapor in the atmosphere. 5. Most unstable layer - fog,clouds,storms etc. |
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Effect of temperature on a fixed volume of air. |
1.Volume changes as temp increases/decreases. 2. Pressure decreases as height increases. 2.5 however, the rate of change of pressure is greatest on cold air |
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International Standard Atmosphere |
1. Pressure of 1013.2 hPa 2. Temperature of +15°C 3. Air density of 1.225 kg/m^3 3. Decrease of temperature of 6.5°C/km up to 11km |
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What is a barometer? |
An instrument for measing atmospheric pressure |
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How does the mercury barometer work? |
It works on the principle that the weight of the overlying air is balanced against the weight of a column of mercury |
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Temperature scales |
Celsius scale is ICAO standard. Fahrenheit is used in US for surface temp |
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What are the common temperature references? |
Melting point and boiling point |
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What is the boiling point for Celsius and Fahrenheit |
100°C 212°F |
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What is the melting point for Celsius and Fahrenheit? |
0°C 32°F |
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What is the formula for F and C |
F=9/5C + 32 C=5/9 (F-32) |
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QFE |
Atmospheric pressure at official aerodrome |
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QNH |
The pressure value to set on the subscale of a pressure altimeter in order that it will read the aerodrome elevation when the aircraft is on the ground station. |
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QNE |
The height indicated on a pressure altimeter when the aircraft is on the ground at the aerodrome and 1013.2 hPa is on the subscale |
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Relative humidity |
Is the percentage degree of saturation. Amount of water in the air to the amount the air can hold at same temp if it were saturated |
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Hygrometer |
Humidity is commonly measured using dry and wet bulb thermometers |
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Temperature - dew point spread |
The difference between the actual air temperature and dewpoint temperature is an indication of how close the air is to saturation. Alsi indicates the possibility of fog formation at an aerodrome. |
