Weather

Question 1

A process of cooling the air through expansion is better known as…

Answer 1

Adiabatic cooling.

Question 2

Does warmer air expand or contract?

Answer 2

Warmer air expands and become lighter and less dense than colder air.

Question 3

In the northern hemisphere, high pressure air circulates…

Answer 3

Outward, downward and clockwise.

Question 4

What is a characteristic of a low pressure system?

Answer 4

Unstable and usually brings increasing cloudiness and precipitation.

Question 5

Adiabatic changes to air imply….

Answer 5

No heat is removed from or added to air as it expands or contracts.

Question 6

Name the 5 temperature variations which create forces that drive the atmosphere its endless motions…

Answer 6

Dirunal, Seasonal, Latitude, Topography and Altitude.

Question 7

Which precipitation type usually indicates freezing rain at higher altitude?

Answer 7

Ice Pellets always indicate freezing rain at higher altitude.

Question 8

After passing thru into a cold front, will atmospheric pressure typically increase or decrease?

Answer 8

When crossing a front directly into colder air, the pressure will usually rise.

Question 9

Where can the maximum hazard zone caused by wind shear associated with a thunderstorm be found?

Answer 9

on all sides and directly under the thunderstorm.

Question 10

What is a microburst? What is a dry microburst?

Answer 10

Microbursts are small-scale intense downdrafts which, on reaching the surface, spread outward in all directions from the downdraft center. A dry microburst often generates a ring of dust on the surface. A microburst is defined if damaging winds extend to 2.2 miles or less horizontally.

Question 11

Do closely spaced isobars indicate stronger or lighter winds?

Answer 11

The stronger the pressure gradient force, the stronger the wind. Closely spaced isobars mean strong winds.

Question 12

What is diurnal variation?

Answer 12

It is the change in temperature from day to night brought about by rotation of the Earth.

Question 13

What is the worst icing condition?

Answer 13

Freezing Rain (FZRA) and Freezing Drizzle (FZDZ).

Question 14

The troposphere is the layer that goes from the surface to approximately what average altitude?

Answer 14

7 miles.it varies with latitude and season, it slopes from 20,000 feet over the poles to 65,000 feet over the equator and is higher in summer than winter.

Question 15

What is the definition of wind shear?

Answer 15

Any rapid change in wind direction or velocity which causes airspeed changes greater than 15 knots or vertical speed changes greater than 500 feet per minute.

Question 16

Freezing rain encountered during a climb is usually indicative of what?

Answer 16

A layer of warmer air above. Rain or drizzle always forms in temperatures above freezing. Rain or drizzle falling thru colder air may become super cooled, freezing on impact as freezing rain.

Question 17

What is a thermal Low?

Answer 17

A dry, sunny region that becomes warm from intense surface heating, thus generating a surface low.

Question 18

Winds aloft are 270/20, they shift to 210/15, have you experienced frontal passage?

Answer 18

Yes, even though shifts are usually to the right after passage. The question I got had to do with ground weather and frontal passage, low ceilings and heavy rain proceeding a cold front.

Question 19

What is the difference between pressure altitude and density altitude?

Answer 19

Pressure altitude is the height above the standard datum pressure (29.92” Hg, sea level under ISA). Density altitude is pressure altitude corrected got nonstandard temperatures. Density altitude is used for determining aerodynamic performance in the nonstandard atmosphere.

Question 20

Standard atmosphere at sea level is 15° and 29.92” Hg, by definition however, how would you describe what standard atmosphere is?

Answer 20

the result is specified sea- d pressure level temperature and specific rates of change of temperature and pressure with height.

Question 21

How far should you fly around a thunderstorm?

Answer 21

avoid any thunderstorms identified as severe or giving an intense radar echo by at least 20 miles if circumnavigating or clear the top of the storm by 1000 feet for every 10 knots of wind speed at the top of the storm if flying over the top.

Question 22

When flying from high pressure to low pressure at constant indicator altitude and without adjusting the altimeter, do you gain or lose true altitude?

Answer 22

You lose true altitude.

Question 23

How is the standard atmosphere determined?

Answer 23

average conditions throughout the atmosphere for all latitudes, seasons and altitudes.

Question 24

What type of icing will cause formation more quickly?

Answer 24

Clear ice. A condition favorable for rapid accumulation of clear ice is freezing rain below a frontal surface.

Question 25

What shows up best on radar? Rain, Hail, Sleet, Snow.

Answer 25

Technically, wet hail has the highest reflectivity of any precipitation, however, for the given choices rain is the most reflective and thus, the correct answer.

Question 26

You experience wind shear on final, what is the best course of action?

Answer 26

While aircraft procedures may vary, the pilot on experiencing severe wind shear should maintain or increase pitch attitude, increase power to the maximum available and accept lower than normal airspeed indications. If this does not arrest the descent, the pilot should continue to pitch up until the descent does stop or until the “stick shaker” is encountered.

Question 27

You are at 25,000ft, there is Level 5 thunderstorm 80 miles in front of you. You tilt your radar up 1.5° and the cell disappears. How high is the Thunderstorm cell?

Answer 27

1° of tilt raises or lowers the beam 1000 feet at a distance of 10 miles. Thus, at 80 miles, 1.5° of tilt = 12,000ft. Add that to 25,000ft = 37,000ft Approx.

Question 28

What are the 3 belts of prevailing winds in the northern hemisphere?

Answer 28

Polar easterlies (north of 60 latitude), prevailing westerlies (between 30 and 60 latitude) and trade winds (between the equator and 30 latitude).

Question 29

What is the definition of severe icing?

Answer 29

When the rate of ice accumulation on an aircraft is such that de-icing/anti-icing equipment fails to reduce or control the hazard.

Question 30

Describe how the general circulation of air in the northern hemisphere from the equator to the poles is formed…

Answer 30

Warm air forced aloft at the equator moves north toward the poles and turns to the right (Coriolis Effect), becoming a westerly wind at about 30 lat. Cool polar air descends and makes its way towards the equator, it too shifts to the right and by the 60 lat forms the polar easterlies. Air piles up at the 30 and 60 lat in both hemispheres. This creates a high press belt that ids the basis for mid-lat band of storms and weather.

Question 31

Are METAR winds reported in relation to magnetic or true north?

Answer 31

True north. Remember, if it’s written, it’s true (expect for the paint on the runway).

Question 32

Does warm air hold more or less water vapor than cold air?

Answer 32

warmer air holds more water vapor.

Question 33

What percentage of the atmosphere is oxygen?

Answer 33

When dry, 21%

Question 34

What is the jet stream and where is it found?

Answer 34

The jet stream is a narrow band of strong wind (by arbitrary definition, it has wind speeds of 50knts or greater) meandering through the atmosphere at a level near the tropopause. The jet stream is always found at a vertical break in the tropopause where the tropical and polar tropopauses meet.

Question 35

The tropopause is of great interest to pilots of jet aircraft two reasons, they are…

Answer 35

there is an abrupt change in temperature lapse rate which affects the performance of a jet engine and maximum winds (i.e. jet stream) and narrow zones of wind shear are found at the tropopause.

Question 36

What are ATIS and METAR winds listed in: mag or true?

Answer 36

METER WIND DIRECTION AND SPEED Direction in tens of degrees from true north…AIM7 -1 -11. AUTOMATIC TERMINAL INFORMATION SERVICE ATIS information includes the time of the latest weather sequence including wind direction (magnetic)… ATIS 4 – 1 -13

Question 37

Everything else being equal, why is a wind blowing across isobars slower at the surface than aloft?

Answer 37

Friction between the wind and the terrain surface slows the wind.

Question 38

Temperature = 58 and Dew Point = 55, what could happen if temperature drops?

Answer 38

when the temperature of the air is reduced to the dew point, the air is completely saturated and moisture beings to condense out of the air in form of fog, dew, frost, clouds, rain, hail or snow.

Question 39

When flying into colder than standard temperatures are you at a higher or lower true altitude than what your altimeter indicates?

Answer 39

You are at lower true altitude.

Question 40

What conditions are conducive to the formation of frost on an airplane?

Answer 40

Clear night, 30°F, Light winds, no precipitation. The temperature of the surface is at or below the dew point of the adjacent air and the dew point is below freezing.

Question 41

CAT is best predicted where horizontal wind shear exceeds what values?

Answer 41

Expect and avoid areas of CAT where horizontal wind shear exceeds 40 knots per 150 NM.

Question 42

In what condition will snowflakes form?

Answer 42

Snowflakes are formed by sublimation in below freezing temperatures.

Question 43

What is terrestrial radiation?

Answer 43

The Earth radiates energy, this outgoing energy is terrestrial radiation.

Question 44

In level flight, you encounter icing conditions and you know your pitot heat is not working, what do you do?

Answer 44

Either descend or climb but get out of icing conditions immediately. A completely blocked pitot tube due to an inoperative heater will cause the airspeed indicator to function like an altimeter.

Question 45

Describe radiation fog…

Answer 45

Usually occurs;
High humidity during the early evening.
Cool cloudless nights with light winds.
Favorable topography.

Question 46

What kind of winds are associated with a warm front?

Answer 46

warm fronts move slowly. Generally the winds in a warm front are from 10-25 mph as opposed to cold. Fronts which move much more quickly and experience wind gusts from 25-35 mph.

Question 47

Mountain waves can produce stationary cloud group of rotor clouds and standing lenticular clouds. Pf the two, which are usually found at lower altitudes?

Answer 47

Rotor clouds are likely to be the lowest.

Question 48

CAT associated with mountain waves can extend how high?

Answer 48

5,000 feet above the tropopause and can travel 100 or more miles downwind from the mountains.

Question 49

What type of weather report would you find CAT on?

Answer 49

Clear Air Turbulence Forecast – CAT (3 and 6 hrs. US Forecast).

Question 50

Describe advection fog…

Answer 50

Forms day or night as a result of moist air moving over a cold surface.

Question 51

Is cooler air more or less dense than warmer air?

Answer 51

cooler air is heavier and sinks becoming more dense than warmer air.

Question 52

How can the stability of the atmosphere be determined?

Answer 52

The best indication of the stability or instability of an air mass is the ambient temperature lapse rate.

Question 53

What percentage of the sun” energy is absorbed by Earth?

Answer 53

About 45%, the other 55% is reflected by the Earth and its atmosphere.

Question 54

What is Atmospheric Pressure?

Answer 54

It is the force per unit area exerted by the weight of the atmosphere.

Question 55

What are the dynamics of a low pressure system?

Answer 55

Air flows from areas of high pressure into areas of low pressure because air always seeks out lower pressure. In the northern hemisphere, the air flows toward a low and is deflected to create a counterclockwise or cyclonic circulation. The air flows into a low pressure area to replace rising air this air tends to be unstable, and usually brings increasing cloudiness and precipitation.

Question 56

Squall lines are typically found ahead of cold or warm fronts?

Answer 56

Typically associated with cold fronts. However, squall lines can form during the summer month as far as 200 miles in advance of a severe cold front.

Question 57

What are the parameters that define wind shear?

Answer 57

Wind shear is defined as “any rapid change in wind direction or velocity”. Severe wind shear is defined as a rapid change in wind direction or velocity causing air speed changes greater than 15 knots or vertical speed changes greater than 500 feet per minute.

Question 58

The most hazardous area or zone caused by wind shear is typically found in this area around a thunderstorm?

Answer 58

On all sides and directly underneath the cell.

Question 59

What does 1013.2mb equate to in inches of mercury?

Answer 59

Standard atmospheric pressure at sea level is 1013.2 millibars, which is the equivalent of 29.92 inches of mercury.

Question 60

Define a mountain wave.

Answer 60

Mountain wave occurs when air is blown over a mountain range or ridge of a sharp bluff. Generally requires winds of 30 knots or greater but may occur with winds as little as 15 knots. Creates strong updrafts/ downdrafts on lee side which can cause turbulence up to 700 miles downrange. May form lenticular clouds over peaks.

Question 61

What percentage of cloud cover is scattered?

Answer 61

Scattered (SCT) is defined as 3/8 to 4/8 coverage. FEW (1/8 to 2/8 coverage), SCT (3/8 to 4/8 coverage), BKN (5/8 to 7/8 coverage) and OVC (8/8 coverage).

Question 62

What affect does surface friction have on wind?

Answer 62

Friction between the wind and the terrain surface allows the wind. The rougher the terrain, the greater the fictional force. Friction is an effective force and always acts to oppose wind direction.

Question 63

What is a pressure gradient force?

Answer 63

Pressure differences must create a force in order to drive the wind. The force is from higher pressure to lower pressure and is perpendicular to isobars or contours. This force is the pressure gradient force.