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NIFE Weather ELOs EXAM WITH 100%
CORRECT ANSWERS
Describe the characteristics of the troposphere - correct answers ✔✔Layer adjacent to earths surface, 55k ft over equator to 28k over poles. avg height is 36k, higher in summer. temp decreases as altitude increases, and nearly all weather occurs here. winds range from light at surface to 200 kts near the top Define atmospheric pressure - correct answers ✔✔the pressure exerted by the weight of the atmosphere over a column of air. what is the standard unit of pressure measurement and atmospheric pressure at sea level - correct answers ✔✔Pressure measurement is measured in inches of mercury (In-Hg) and millibars. standard measurements are 29.92 in-hg and 1013.25 mb explain a pressure gradient - correct answers ✔✔rate of pressure change perpendicular to the isobars. stronger when isobars are closer together. Standard Lapse Rate - correct answers ✔✔ 2 °c/1,000ft 3.6 F/1000ft
rate at which temperature decreases with altitude. what is a standard atmosphere - correct answers ✔✔29.92 hg or 1013.2mb 15 C or 59 F 1"hg/ 1000ft. or 34 mb/1000ft. 2 C / 1000ft or 3.5 / 1000ft LSOS 661.7 knots or 340.4 m/s What is the difference in sea level pressure and station pressure - correct answers ✔✔Station pressure is the atmospheric pressure measured directly at an airfield or other weather station. sea level pressure is the pressure that would be measured if the eisting weather station were at MSL. Sea level pressure can always be calculated from station pressure by adding or subtracting the standard lapse rate. define an air mass - correct answers ✔✔Body of air that's humidity and temperature are almost uniform throughout. warm air masses bring stable conditions, and cold air masses are usually unstable. cold air masses come from north and move cold air over warm surfaces, and warm air masses come from south and are warmer over the surface. Describe saturation - correct answers ✔✔Saturation is when the air contains the maximum amount of water vapor it can hold for that temperature.
Above Ground Level (AGL) - correct answers ✔✔Height above the ground over which you're flying Pressure Altitude - correct answers ✔✔The height above the standard datum plane. actual elevation from standard pressure plane of 29.92 in-hg. Density Altitude - correct answers ✔✔The pressure altitude corrected for nonstandard temperature. Pressure changes effects on aircraft altimeters - correct answers ✔✔As an aircraft flies from high to low pressure: "look out below" as your airplane will be lower than your indicated altitude. As an aircraft flies from low to high: "plenty of sky" as your aircraft will be higher than indicated altitude. A change in pressure of .10 In-Hg will change the altimeter setting 100 feet. How does temperature deviations from standard lapse rate effect aircraft altimeters - correct answers ✔✔for every 11 deg C that the temp varies from standard, the altimeter will have a 4 percent error. If temp is LOWER than standard: Aircraft will be higher than indicated. If temp is HIGHER than standard: aircraft will be lower than indicated.
Define Temperature inversion - correct answers ✔✔A temperature inversion is when the temperature rises with altitude instead of falls. Explain and identify gradient winds with respect to isobars around pressure systems in northern hemisphere - correct answers ✔✔Air circulates parallel (or close to parallel) to isobars, and CLOCKwise around high pressure and COUNTERCLOCKwise around low pressure. Identify surface wind direction with respect to gradient winds in a pressure system in the Northern Hemisphere - correct answers ✔✔Pressure gradient force (high to low pressure force) causes air to flow perpendicular to isobars, however when coriolis force is added, this diverts the air to the right with respect to its inital direction of motion. Thus the combination of these forces produces the CW motion around high and CCW motion around low Found Above 2000 Ft. Surface winds - correct answers ✔✔Blow at a 45 degree angle relative to parallel flow CW around high and CCW around low describe the jet stream - correct answers ✔✔Strong, narrow band of high speed wind in upper troposphere. winds average 100-150 knots but may reach in excess of 250 knots. Usually found in segments of 1000-3000 miles in length, 100-400 miles in width and 3000- feet in depth.
in intensity, then as front passes, pressure rises sharply, and winds shift from SW to NW. post frontal weather includes rapidly clearing skies, fair weather cumulus clouds and decreasing temp and dew point. How it affects flight: fast moving cold fronts contain rough weather for roughly 50 miles. Slow moving can affect flight conditions for hours. Expect turbulence in vicinity of cold front. Icing may be severe in cumuliform clouds describe the characteristics of a squall line - correct answers ✔✔Contain extremely violent thunderstorms. develop 50-300 miles ahead of the cold front. Forms when cold air downdrafts flowing ahead of a cold front lift additional warm, unstable air. Usually impossible to fly through, and have wind shift 90 degrees from the SW to the NW. Describe the characteristics of a warm front including wind shift, ceiling and vis, turbulence and thunderstorms, and precipitation and icing. - correct answers ✔✔Warm air moves and rides over the cold air mass. Typically moves at a slower pace than a cold front, about 15 knots. Because of this slow speed they also have a more gradual slope along the surface front, which brings less severe weather Wind shifts are typically from the SE to the SW. Recognized by stratiform clouds. if approached from the east, cirrus, cirrostratus, altostratus and then nimbostratus and finally stratus clouds with rain and fog. Usually have steady precipitation. turbulence not likely as wind shifts are not as sudden. Ceilings are low, usually 300-900 agl from stratus clouds.
thunderstorms can form if the advancing front is unstable, and are usually concealed. Only turbulence encountered would be in these thunderstorms. If approaching from the warm air side, precipitation usually begins around the 8000- cloud deck and increases the closer to the front you get. Icing may occur depending on the temperature and will take a long time to climb out of, so look to descend to warmer air. describe characteristics of a stationary front - correct answers ✔✔frontal borders show no movement. winds tend to blow parallel to the front, so there is a 180 degree wind shift. Weather is similar to a warm front, but less intense. Describe characteristics of a occluded front - correct answers ✔✔Faster cold front overtakes slower warm front. cold and warm. type of occluded front is determined by which air mass stays in contact with the ground. Tend to be aligned NW-SE. wind shift will be 180 degrees. Weather depends on the direction you approach. if you approach from the warm front side, you will encounter warm front weather and wind shift, if you approach from the cold front side you will encounter cold front weather. occluded front wave formation - correct answers ✔✔ Explain the relationship of flight conditions and atmospheric stability - correct answers ✔✔Stable: Temperature inversions, low fog, stratus clouds, rising air temperature while climbings.
Describe Low clouds and their characteristics. - correct answers ✔✔Low clouds: surface to 6500 ft. consists of water droplets. Most serious hazard is the close proximity to the surface, reducing visibility and ceiling. icing accumulates faster due to increased density, expect icing and none to moderate turbulence in low clouds. Usually a light rain or drizzle from low clouds Describe the two principle cloud forms - correct answers ✔✔Cumuliform: Lumpy, billowy cloud with a base showing pattern or structure Stratiform: Uniform base, formed in horizontal, sheet like layers Describe middle clouds and their characteristics. - correct answers ✔✔Middle Clouds: 6500- 20000 ft. contains prefex-ALTO. composed of ice crystals, water droplets and a mix. Visibility in clouds ranges from a few feet to 1/2 mile. icing is common due to supercooled water droplets and turbulence is also present. Describe high clouds and their characteristics. - correct answers ✔✔High clouds: above 20000. average from 20000 to 40000 foot bases. Little effect on flying except moderate turbulence and limited visibility associated with dense jet stream cirrus clouds. mainly composed of ice crystals, so icing is not an issue. Describe Special clouds and their characteristics. - correct answers ✔✔special clouds with vertical development: towering cumulus (near thunderstorm, heavy rain showers and moderate turbulence near the cloud. Icing common above freezing) and cumulonimbus clouds (thunderstorms. very dangerous, extreme turbulence, hail, icing, etc). Bases at low to middle heights and extend upwards into the high cloud category. Nimbostratus produces continuous rain, snow or ice. Bases commonly around 1000 AGL with fog, and poor vis. Define turbulence - correct answers ✔✔Any irregular or disturbed flow in the atmosphere producing gusts or eddies.
List intensities of turbulence - correct answers ✔✔Light: monetarily causes slight erratic changes in altitude or attitude or slight rapid rhythmic bumpeness without any appreciable changes in altitude or attitude. Moderate: Similar to light but of greater intensity. Food service difficult. severe: large, abrupt changes in altitude or attitude,and variations in indicated airspeed. Aircraft may be momentarily out of control. food service impossible. Extreme: aircraft violently tossed around and practically impossible to control. May cause structural damage. list turbulence terminology with respect to time - correct answers ✔✔Occasional: less than 1/ intermittent: 1/3-2/ continuous:>2/ list causative factors that create various types of turbulence. - correct answers ✔✔Thermal, mechanical, frontal, and large scale wind shear. How does thermal turbulence develop - correct answers ✔✔Localized convective currents resulting in surface heating or cold air moving over warmer ground. Also includes strong solar heating. Certain types of surfaces heat quicker: more barren=more heat absorption quicker, so expect turbulence over these areas.
Primary hazard of low level wind shear turbulence - correct answers ✔✔being forced into the ground recommended procedures for flight through turbulence - correct answers ✔✔Establish thrust and attitude settings for Va, do not chase airspeed. Trim for level flight. do not change trim. proper attitude must be maintained. Do not make abrupt control inputs to avoid overstressing aircraft. allow altitude to vary with extreme gusts. turbulence associated with thunderstorms - correct answers ✔✔Turbulence can be encountered several thousand feet above and 20 miles laterally from a severe storm. Severe turbulence in the anvil 15-30 miles downwind. describe structural icing - correct answers ✔✔ice that forms on the exterior of an aircraft. describe the requirements for structural icing - correct answers ✔✔1: supercooled water droplets 2: free air temperature (temp taken outside of the airplane) and aircraft surface must be below freezing. Temperature range most conductive to icing - correct answers ✔✔Any cloud below 0 degrees C, but above -20 degrees C.
clear icing Normally occurs between 0 and -10 C. tough to break off and hard to see. Most hazardous Rime icing normally occurs between -10 and -20 degrees C. easy to break off and visible. mixed icing normally occurs from -8 to -15 degrees C list hazards of aircraft icing - correct answers ✔✔disrupts smooth airflow over airfoils, increases drag and stall speed, more fuel consumption, thrust and range decrease, increased weight. can also increase stress on aircraft parts due to the delicate balance. can also block pitot tube causing erroneous indications. Cues and signs of aircraft icing - correct answers ✔✔If you encounter any type of freezing rain or drizzle, best to leave the area. cues include erroneous indications of altitude and airspeed, ice on windshield or wiper arms, or other protruding aircraft parts, decreasing airspeed with constant power and altitude, and ice detector annunciation. on rotor, serious vibration, loss of efficiency or control, and reduced RPMs. Procedures to avoid aircraft icing - correct answers ✔✔1. Don't fly into areas of known or forecast icing conditions.
- Avoid flying in clouds with temperatures from 0° C to -20° C.
- Don't fly through rain showers or wet snow with temperatures near freezing.
decreases, the fuel-air ratio increases, which in turn raises the temperature of the gases going to the turbine. The fuel control attempts to correct any loss in engine RPM by adding more fuel, which merely aggravates the condition. Icing intensity classifications - correct answers ✔✔Trace: Rate of accumulation is slightly greater than sublimation. Not dangerous even without deicing/anti icing agents unless encountered for over 1 hour. Light: Does not present problem if deicing equipment is used, but without equipment can create problems. Moderate: short encounters become potentially hazardous, deicing equipment or diversion is Necessary. Severe: deicing equipment does not work, and immediate diversion is necessary. Parameters that define fog - correct answers ✔✔Visible aggregate of minute water droplets that is within 50 feet of the surface, greater than 20 ft in depth and reduces prevailing visibility to less than 5/8 of a statue mile. Describe obscuring phenomena - correct answers ✔✔Haze: bluish color against ground, most common at low levels, associated with stable atmosphere. looks like horizon above the layer. smoke: sunrise/sunset appear red. reduces visibility similar to haze. rain and drizzle: feature of stable air and can reduce visibility. snow: can reduce visibility much more than rain or drizzle and can reduce visibility to less than one mile
blowing snow: associated with turbulence, and can blow from the surface obscuring surface visibility. Dust and sand: unstable air, usually limited to less than 100 feet. common behind cold fronts moving across prairies in early spring before vegetation has appeared. What is required for fog formation - correct answers ✔✔1: condensation nuceli must be present 2: air must have high water content and low dew point spread 3: Light surface winds must be present. Describe two main types of fog - correct answers ✔✔The two main types of fog are radiation fog and advection fog. Radiation fog occurs due to nocturnal cooling, usually on clear nights, when the Earth releases relatively large amounts of radiation into the atmosphere, cooling the surface. If nocturnal cooling reduces the air temperature to the dew point temperature, fog or low ceiling clouds will develop in the area. Advection fog occurs when warm, moist air moves over a cold surface and the air is cooled to below its dew point. Common in coastal areas, it is often referred to as sea fog when observed to come from the sea. Fog of this type becomes thicker and denser as the wind speed increases, up to about 15 knots. Describe hazards associated with thunderstorms - correct answers ✔✔Strong wind gusts, severe turbulence, lightning, heavy rain showers, severe icing, possibly hail, lightning and electrostatic discharge (can cause damage to electronics, aircraft skin perforations, and temporary blindness) and tornados.
- Establish the recommended turbulent air penetration speed and disengage the autopilot to minimize control inputs that could increase structural stresses.
- Don't chase the airspeed and minimize power changes. Expect significant deviations in attitude and altitude. Keep your eyes on your instruments.
- Don't turn back once in the thunderstorm. Flying near thunderstorm procedures - correct answers ✔✔1. If at all possible, avoid thunderstorms.
- Do not venture closer than 20 miles to any storm cloud with overhanging anvils because of the possibility of encountering hail.
- Do not attempt to fly under thunderstorms in mountainous regions even if the area on the other side of the mountains can be seen. Winds that are strong enough to provide the lifting action to produce the thunderstorms can also create extreme turbulence between mountain peaks.
- If at all possible, avoid flying under thunderstorms because updrafts and downdrafts can exceed the performance of the aircraft.
- Do not take off or land if a thunderstorm is approaching. Sudden wind shifts or microbursts can cause control problems.
- Do not fly into a cloud mass containing scattered embedded thunderstorm without airborne radar. Radar is necessary to "see" storms in the cloud mass. Scattered thunderstorms can be circumnavigated visually unless they are embedded.
- To avoid lightning do not penetrate a thunderstorm or fly through the cirrus anvil of a well- developed or dissipated thunderstorm. Aircraft should also avoid clouds downwind of thunderstorms.
- The brighter and more frequent the lightning, the more severe the thunderstorm.
- Regard any thunderstorm with tops 35,000 feet or higher as severe DEFINE the types of visibility: Flight visibility, prevailing, runway visual range, vertical visibility and slant visibility - correct answers ✔✔Flight Visibility - The average forward horizontal distance, measured in statute miles from the cockpit of an aircraft in flight, at which a pilot can see and identify prominent unlighted objects by day and prominent lighted objects at night.
Prevailing Visibility - The greatest horizontal visibility, measured in statute miles, equaled or exceeded throughout at least half the horizon circle, which need not be continuous. Slant Range Visibility - The distance on final approach when the runway environment is insight. This is probably the most vital weather information needed during a final approach in questionable weather. Runway Visual Range (RVR) - The horizontal distance, expressed in hundreds of feet or meters, a pilot will see by looking down the runway from the approach end. Vertical visibility: Distance seen directly upward from the ground into a surface based obscuring phenomenon Define sky coverage terms that define ceiling - correct answers ✔✔SKC or CLR: clear 0/ Few >0/8-2/ SCT: 3/8-4/ BKN:5/8-7/ OVC: 8/ VV: Surface Based obscuration CLR: no clouds at or below 12000, SKC: no clouds reported Describe use of PIREPs, report conditions and format - correct answers ✔✔PIREPs are reports given by pilots to supplement ground station weather observations. solicited from ATC when ceilings are at or below 5000, vis is at or below 5 miles, thunderstorms or related phenomena, icing of a light degree or greater, turbulence of a moderate degree or greater and wind shear.
