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NIFE Weather Exam With 100% Correct
Answers
Describe the characterisitcs of the troposphere - correct answers ✔✔The average height of the troposphere is 36,000 feet. Within the troposphere, temperature normally decreases with an increase in altitude. Nearly all winds occur in the troposphere, and increase with altitude. The tropopause is a transition zone between the troposphere and the stratosphere. 78% nitrogen, 21% oxygen, 1% other Define atmospheric pressure - correct answers ✔✔The pressure exerted on a surface by the atmosphere due to the weight of the column of air directly above that surface. Always decreases with altitude. State the standard units of pressure measurement - correct answers ✔✔Inches of mercury (In- Hg), and millibars (mb) Explain the term pressure gradient - correct answers ✔✔The rate of pressure change in a direction perpendicular to the isobars. Isobar spacing represents the size of the pressure gradient force (PGF). Close together = steep/strong, spaced = shallow/week. PGF is the initiating force for all winds Define a lapse rate - correct answers ✔✔The decrease in atmospheric temperature with increasing altitude State the average temperature lapse rate in degrees celsius - correct answers ✔✔A 1000 foot increase in altitude will result in a temperature decrease of 2 degrees celsius (3.5 F)
Define the standard atmosphere - correct answers ✔✔Standard day conditions are sea level, pressure 29.92 in Hg (1013.2 mb) and 15 degrees celsius (59 F) Differentiate between 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 from the existing weather if the station were at MSL - can be measured directly at sea level, or calculated if the station is not at sea level using the standard lapse rate. Define the types of altitude - correct answers ✔✔Indicated Altitude is the altitude read directly from the altimeter. Calibrated altitude is indicated altitude corrected for instrument error. Pressure altitude is the height above the standard datum plane (altitude when barometer is set to 29.92 in Hg). Density Altitude is pressure corrected for nonstandard temperature deviations. Mean sea level is the actual height above sea level, it is found by correcting calibrated altitude for temperature deviations from the standard atmosphere. AGL is the aircraft's height above the terrain directly beneath the aircraft and is measured in feet above ground level. Define indicated altitude - correct answers ✔✔Indicated Altitude is the altitude read directly from the altimeter. Describe the effects of pressure changes on the aircraft altimeters - correct answers ✔✔As sea level pressure on the surface decreases, the whole column of air aloft is lowered, causing an aircraft flying at an assigned MSL altitude to descend to a lower AGL altitude High to low, lookout below Low to high, plenty of sky
high pressure to low pressure across the isobar pattern. The Coriolis effect diverts air to the right, with respect to its initial direction of motion, regardless of whether the air is near a high or a low pressure system. The result of these two forces is the gradient winds, which flow perpendicular to the pressure gradient force. Gradient winds flow parallel to the isobars, and the resulting circulation flows clockwise around highs and counterclockwise around lows. Above 2000 AGL Explain and identify the surface wind direction with respect to the gradient winds in a pressure system in the northern hemisphere - correct answers ✔✔Surface friction reduces the speed of the wind, which causes a reduction in the coriolis force. WHen the balance of forces is reached, the air blows at an angle across the isobars from high pressure to low pressure. Assume a 45 degree angle. Coriolis still tries to turn the wind to the right, but not as much as gradient winds. Surface winds still move clockwise around highs and counterclockwise around lows, but also have a component of motion that moves air out of the high pressure and into the low. Below 2000 AGL Describe the jet stream - correct answers ✔✔A narrow band of strong winds of 50 kts or more that meanders vertically and horizontally around the hemisphere in wave-like patterns. Winds average 100-150 knots but can exceed 250 kts. Found in segments 1000-3000 miles long, 100- 400 miles wide, and 3000-7000 feet deep. Average height is around 30,000 MSL. Describe sea breezes - correct answers ✔✔During the day, the pressure over the warm land becomes lower than that over the colder water. The cool air over the water moves toward the lower pressure, replacing the warm air over the land that moved upward. The resulting onshore wind, blowing from the sea, is called a sea breeze, with speeds sometimes reaching 15 to 20 knots. Describe land breezes - correct answers ✔✔At night, the circulation that causes sea breezes is reversed so that the air movement is from land to sea, producing an offshore wind called the land breeze
Define the term front - correct answers ✔✔An area of discontinuity that forms between two contrasting air masses when they are adjacent to each other. Describe the discontinuities used to locate and classify fronts - correct answers ✔✔TDWP (TouchDowns Win Points) Temperature Dewpoint Winds Pressure Describe the characteristics of cold, warm, occluded, and stationary fronts - correct answers ✔✔Cold - move SE at 20 kts, wind shift SW to NW. Identified by a long line of cumuliform clouds. Blue spiked line. Warm - move NE at 15 kts, wind shift SE to SW. Red bumpy line. Gradual precipitation increase. Occluded - Cold front overtakes a warm front. Named cold/warm occluded depending on which front remains in contact with the ground. 180 degree wind shift. Purple line with both symbols pointed the same direction. Stationary - Has a 180 degree wind shift. Red and blue symbols in alternating directions. Describe the characteristics of a squall line - correct answers ✔✔A line of violent thunderstorms. Indicated by a dashed, double dotted red line. Develops ahead of a cold front. Have a 90 degree wind shift from SW to NW Explain the relationship between flight conditions and atmospheric stability - correct answers ✔✔FATVIPWC Front Airmass Turbulence Visibility Icing Precipitation Winds Cloud types WWSPRSSS Warm Warm Smooth Poor Rime Steady Steady Stratus CCRGCSGC Cold Cold Rough Good Clear Showery Gusty Cumulus
Define turbulence - correct answers ✔✔Any irregular or disturbed flow in the atmosphere producing gusts and or eddies List the intensities of turbulence used in PIREP's - correct answers ✔✔Light Moderate Severe Extreme Define the terms used to report turbulence with respect to time - correct answers ✔✔Occasional - less than 1/3 of the time Intermittent - 1/3 to 2/3 of the time Continuous - more than 2/3 of the time. Describe how thermal turbulence develops - correct answers ✔✔Caused by localized vertical convective currents resulting from surface heating or cold air moving over warmer ground. Describe how mechanical turbulence develops - correct answers ✔✔Results from wind flowing over or around irregular terrain or other obstructions. When the air near the surface of the Earth flows over obstructions, Normal horizontal wind flow is disturbed and transformed into a complicated pattern of eddies and other irregular air movements. Describe how frontal lifting creates turbulence - correct answers ✔✔Caused by lifting of warm air by a frontal surface leading to instability, or by the abrupt wind shift between the warm and cold air masses. Describe how temperature inversions are examples of wind shear turbulence - correct answers ✔✔Temperature inversion can cause turbulence at the boundary between the inversion layer and the surrounding layer.
Describe the primary hazard of low level wind shear turbulence - correct answers ✔✔Most dangerous due to local phenomenon such as a temperature inversion Describe how jet streams are examples of wind shear turbulence - correct answers ✔✔There is a rapid change in wind speed within a short distance of the jet core. In order to get out, climb if temp is rising, descend is temperature is falling. Describe the recommended procedures for flying through turbulence - correct answers ✔✔Maintain power setting consistent with the aircrafts recommended airspeed for turbulence penetration, trim aircraft for level flight, do not chase airspeed or altimeter, maintain pitch and bank Describe structural icing - correct answers ✔✔icing that forms on the external structure of an aircraft. Structural ice forms on the wings, fuselage, antennas, pitot tubes, rotor blades, and propellers. Significant structural icing on an aircraft can cause control problems and dangerous performance degradation. The types of structural icing are clear, rime, mixed, and frost. 4 levels are Trace, Light, Moderate, Severe State the requirements for the formation of structural icing - correct answers ✔✔The atmosphere must have supercooled visible water droplets, and the air temp and aircraft's surface temp must be below freezing. State the temperature range most conducive to structural icing - correct answers ✔✔Below 0 degrees celsius, ranges -10 to -40 celsius. Clear ice forms 0 to - Rime ice forms -10 to - Mixed ice form -8 to -
Describe the two main types of fog - correct answers ✔✔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. Advection fog occurs when warm, moist air moves over a cold surface and the air is cooled to the dew point. Can stay in an area for weeks Describe the hazards associated with thunderstorms - correct answers ✔✔HIMELT Hail, Icing, Microbursts, Extreme Turbulence, Lightning, Tornadoes Describe the signs and hazards associated with microbursts - correct answers ✔✔Severe downward atmospheric flow with velocities 2000 to 6000 feet per minute Describe the recommended techniques for avoiding thunderstorm hazards - correct answers ✔✔1. Fly around
- Fly over
- Fly under
- Through (bottom 1/3) Define the types of 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. Describe the sky coverage terms that define a ceiling - correct answers ✔✔SKC/CLR - Sky Clear, 0/ FEW - few, 0/8 - 2/ SCT - 3/8 - 4/ BKN - Broken - 5/8 - 7/ OVC - Overcast - 8/ VV - Vertical Visibility Obscured - 8/ Describe the use of PIREP's - correct answers ✔✔Report when: Inflight requested Unusual or unforecast weather Weather conditions are different from the latest observation Missed approach due to weather Wind shear on departure Describe in-flight weather advisories - correct answers ✔✔PIREP's, ATIS Describe the use of surface analysis charts - correct answers ✔✔The Surface Analysis Chart depicts pressure centers, fronts, and barometric pressure lines. Represents past history, and is not a forecast.
State the requirements for obtaining a preflight weather briefing - correct answers ✔✔
