Meteorology Flashcards

Flashcards based on lecture notes for meteorology review.

Below the tropopause, what does the ICAO Standard Atmosphere (ISA) assume?

A mean sea level pressure of 1013.25 hPa together with a mean sea level temperature of 15°C, decreasing at a rate of 2°C per 1000ft until it reaches -65.6°C at 36 090ft.

Where is most of the water vapour in the atmosphere contained?

Troposphere.

What are the proportions of gases in the atmosphere?

Oxygen 21%,Nitrogen 78% other gasses 1%.

What is the layer closest to the earth's surface where the majority of weather is found called?

Troposphere.

The temperature at 2000ft above mean sea level is forecast to be 5°C; compared to the ICAO Standard Atmosphere (ISA) this is:

ISA -6.

What is the name of the instrument which gives a continuous printed reading and record of the atmospheric pressure?

Barograph.

How does the pressure of the atmosphere change with increasing height?

Decreases at a decreasing rate as height increases.

What is the significance of tightly spaced isobars?

A large pressure gradient and strong winds.

What is a line drawn on a chart joining places having the same barometric pressure at the same level and at the same time?

An isobar.

Compared to ISA, what does warm air do to the distance represented by a 1 hpa change in pressure?

Increases it.

What is the density at sea level in the International Standard Atmosphere?

1.225g/m³.

When will density at the surface be low?

Pressure is low and temperature is high.

Generally as altitude increases, what happens to temperature, pressure, and density?

Temperature, pressure and density decreases.

What is density defined as?

Mass per unit volume.

Under what conditions would density be the least at any given place?

High altitude, high temperature and low humidity.

Consider the following statements about air density and select the one which is correct?

Air density decreases with increase of height in the International Standard Atmosphere (ISA).

What reduces the diurnal variation of temperature?

Reduced anywhere by the presence of cloud.

If temperature remains constant with an increase in altitude there is:

An isothermal layer.

A trough of low pressure at the surface is generally associated with:

Convergence causing increased cloud and precipitation.

During the winter months, which of the following weather conditions would most likely be produced by an anticyclone?

General subsidence with adiabatic warming, clear skies, and an inversion.

How will the diurnal variation of the surface temperature change as wind speed increases?

Decrease as wind speed increases.

An area of indeterminate pressure between two lows and two highs is called:

A col.

The method by which energy is transferred from one body to another with which it is in contact is called:

Conduction.

The sun gives out ____ amounts of energy with ____ wavelengths. The earth gives out relatively ____ amounts of energy with relatively ____ wavelengths:

Large / small / small / large.

What happens during an inversion?

There is an increase of temperature as height increases.

Which of the statements below best describes a Col?

An area between two highs where the isobars are very close together.

A ridge of high pressure is generally associated with:

Subsidence of air, then divergence at the surface causing clear skies and poor visibility.

When flying towards a depression at a constant indicated altitude, the true altitude will be:

Lower than indicated.

When an altimeter sub scale is set to the aerodrome QFE, the altimeter reads:

Zero at the aerodrome reference point.

The altimeter will always read:

The vertical distance above the pressure level set in the sub scale.

An aircraft flies at a constant indicated altitude from airfield A (QNH 1009 hPa) to airfield B (QNH 1019 hPa). If the subscale is not reset from 1009, what would be expected when over airfield B:

Indicated altitude to be less than actual altitude.

An aircraft flies from aerodrome "A", where QNH is given as 1020 hPa, to aerodrome "B", where the QNH is given as 999 hPa. Aerodrome "A" is 800ft above mean sea level and aerodrome "B" is 500ft above mean sea level. If the altimeter sub scale is not changed from 1020, what is the altimeter indication on landing? (ASSUME 1 hPa = 30ft)

100 ft.

You experience a constant drift to the right when flying over Europe at a constant indicated altitude. If the altimeter subscale is not updated, this will result in?

Flying at a progressively lower true altitude.

You are flying at a constant indicated altitude with the QNH of 1015 set within the subscale and you notice the outside air temperature has been falling constantly. What can you expect to have happened to your true altitude?

Decreased.

The instrument used for measuring the humidity of air is a:

Hygrometer.

When condensation takes place, the higher the temperature the ____ the amount of latent heat ____:

Greater / released.

Wet bulb temperature would normally be lower than dry bulb temperature because:

Evaporation causes cooling on the wet bulb thermometer.

The process of change of state from a gas to a liquid is known as:

Condensation in which latent heat is released.

A change of state directly from a solid to a vapour or vice versa is:

Sublimation.

During a night with a clear sky, surface temperature will ____, relative humidity will ____ and dewpoint will ____.

Fall / Rise / Remain the same.

Which of the processes listed below can cause air to become saturated?

Evaporation.

Given an atmospheric situation where the relative humidity is 60% and the ELR is less than the DALR, if air is forced to rise it will be:

Stable and will tend to regain its former position.

The pilot of an aircraft which is approaching a mountain from the downwind or leeward side, a few hundred feet above ridge level, observes venticular clouds. Which of the following conditions would the pilot expect to encounter as the flight continues?

Strong down-draughts immediately before the ridge of the mountain is reached, with strong up-draughts after passing the ridge to the windward side.

The actual change of temperature with height is known as:

The environmental lapse rate.

Which of the following is true about the lowest level windshear?

It may be experienced 15 to 20 miles ahead of a fast moving thunderstorm.

An aircraft is flying in the vicinity of a range of hills, lying north-south, across which a wind is blowing from the west to east. Which of the following situations might cause the aircraft to encounter dangerous downdraughts?

When flying west towards the hills from the east.

In a mountain wave situation, the worst of the turbulence is most likely to be found when flying:

In or just below the roll cloud.

A light aircraft flying at low level near a mountain range across which a strong wind is blowing may expect: 1. Severe turbulence below or within any rotor zone. 2. Down-draughts which may exceed the climb rate of the aircraft. 3. A greater than normal risk of icing in the cloud over the crest mountain. 4. Lenticular cloud

Only 1, 2 and 4 are correct.

One or more coloured rings around the sun or moon may indicate the presence of which type of cloud?

Altostratus or cirrostratus.

Given a surface temperature of +21°C and a dew point of +7°C, at approximately what height will the cloud base of a cumulus cloud be?

4.000ft.

Hail is most likely to fall from which type of cloud?

CB.

From the list below, select the Low, Medium and High clouds in ascending order.

Stratus, Altocumulus, Cirrus.

The use of the suffix "nimbus" or the prefix "nimbo" means?

Rain bearing.

Precipitation produced by stratus is normally?

Drizzle.

Unstable air is forced to rise up the side of a mountain. What weather might you expect to see on the windward slopes?

Cloud of extensive vertical development.

The conditions which must exist to allow thunderstorms to develop are:

A plentiful supply of moisture and a steep lapse rate through a large vertical extent, together with a trigger action.

Which of the following combinations of weather-producing variables would be most likely to result in cumuliform clouds, good visibility, showery rain, and possible clear type icing in clouds?

Unstable moist air and orographic lifting.

During the ____ stage of a thunderstorm ceil, the cloud contains ____. Complete the above statement choosing one of the following combinations of words:

Mature / up currents and down currents.

What stage of a thunderstorm is characterised predominantly by downdraughts?

Dissipating stage.

For cumulonimbus clouds to develop, there needs to exist:

A deep layer of very unstable moist air.

What stage of a thunderstorm is characterised by updraughts only?

Initial stage.

Which of the following conditions are most likely to produce thunderstorms?

A high moisture content with a steep lapse rate.

Hazards to aircraft caused by the presence of cumulonimbus or thunderstorm cloud may be experienced:

When the aircraft is in the vicinity.

Hazards of the mature stage of a thunderstorm cell include lightning, turbulence and:

Icing, microburst and windshear.

The wind at 2000 ft over an aerodrome was reported at 330/15kt. Using the rule of thumb, what might you expect the surface wind to be?

300/07 kt.

Coriolis force in the Northern Hemisphere will cause moving air to be apparently deflected to:

The right and cause the geostrophic wind to blow parallel to the isobars at about 2.000ft agl.

Winds that blow around an anticyclone (high pressure system) at lower levels in the Northern Hemisphere are represented on a low level chart as blowing in:

A clockwise direction.

Low level winds in the northern hemisphere that blow around a depression are drawn on surface weather charts in?

An anticlockwise direction.

The formation of advection fog is often caused by?

A warm moist air mass under the influence of a moderate wind being cooled to below its dew point by flowing over a much colder surface.

A low level mist layer significantly reduces forward visibility when flying at about 2000ft. To improve your forward visibility you should:

Fly higher.

Which of the following conditions is most favourable to the formation of radiation fog?

High relative humidity, light winds and a clear sky.

Over an inland airfield radiation fog is reported in the morning. As the wind speed increases to 10 kt what would you expect?

The fog to lift and form low stratus.

What are the characteristics of the passage of a cold front?

A dew point fall, a temperature fall, and the wind veering.

If a cloudy, granular type of ice is seen to collect and protrude forward from the leading edge of the aerofoil, what type of ice would it most likely be?

Rime ice.

What will normally happen to the surface wind direction following the passage of a warm front?

Veer.

The extent of rainfall ahead of a typical warm front may be up to a distance of:

200 miles ahead of the surface position of the warm front.

Which of the following frontal systems is more likely to produce thunderstorm activity?

A cold front.

Clear ice forms as a result of:

Large supercooled water droplets spreading as they freeze.

What would be the change in weather following the passage of a typical warm front?

Pressure increases steadily, no more than 4 oktas of cloud, and good visibility.

What is the main reason water can exist in a liquid state even though the temperature is sub zero?

No freezing nuclei.

You are flying above the freezing level in the cold air just ahead of a warm front. If rain were to fall in this area, what kind of icing might you expect?

Rain or clear ice.

Which of the following correctly decodes the METAR shown below? METAR EGKL 130350Z 32005KT 0900 0400N DZ BCFG VV002

Observed on the 13th day of the month at 0350Z, surface wind 320°True, 05kt, current visibility 900 metres, minimum visibility 400 metres to the north, moderate drizzle, with fog patches and a vertical visibility of 200ft.

When a TREND is included at the end of an aviation METAR, the trend is a forecast valid for:

1 hour after the time of observation.

The visibility group R20/0050 in a METAR means:

For runway 20, a current visibility of 500 metres measured by runway visual range equipment.

The code "BECMG FM 1100 -SHRA" in a METAR means:

Becoming, from 1100 UTC, slight rain showers.

A temperature group of 28/24 in a METAR means that:

The temperature is 28°C and the dew point is 24°C.

In the METAR shown below, the cloud base has been omitted. At what height might you expect the cloud base to be if cumulus cloud was present? 28005KT9999 SCT??? 12/05 Q1020 NOSIG

SCT028.

Providing the minimum sector altitude is not a determining factor, CAVOK in a TAF or METAR:

Means visibility 10km or more, and no cloud below 5.000ft.

Which of the following correctly decodes a TAF that reads: LYBE 161100Z 1612/1712 VRB08KT9999 SCT025?

Valid from 1200 Hr on the 16 of the month to 1200 Hr on the 17 of the month; surface wind will be variable in direction at 8kt with a visibility of 10km or more; 3to4 oktas of cloud with a base of 2.500ft above the aerodrome.

BECMG 1621/1701 BKN030 in a TAF means:

Becoming between 2100 UTC on the 16 of the month and 0100 UTC on the 17 of the month 5-7 oktas of cloud at 3000 ft agl.

What does this symbol represent on a forecast chart?(See LAPL/PPL 050-03)

Severe turbulence.

What does this symbol represent on a forecast chart? (See LAPL/PPL 050-04)

Severe icing.

What is the validity time for a WAFC significant weather chart?

For a single fixed time only.

On WAFC significant weather charts what do the letters "CB" implies?

Moderate to severe icing and turbulence.

A regional is a forecast of the weather up to?

FL100.

VOLMETS are updated?

Every half an hour.

VOLMETS is defined as:

A continuous radio broadcast of selected aerodrome actual weather observations and forecasts.

VOLMETS are?

Ground to air radio transmissions on HF and VHF.

When are ATIS broadcasts updated?

Any time the aerodrome or weather information changes.

What is the ATIS?

A continuous broadcast of current aerodrome and weather information.