Meteorology Chapter 7 Flashcards

Questions and Answers

What accompanies every physical process of weather?

Heat exchange

What causes variations in altimeter settings between weather reporting points?

Unequal heating of the Earth's surface

The difference in wind direction at different altitudes is primarily due to what?

Friction between the wind and the surface

What causes convective circulation patterns associated with sea breezes?

Cool, dense air moving inland from over the water Signup and view all the answers

One in-flight condition necessary for structural icing to form is?

Visible moisture Signup and view all the answers

In which environment is aircraft structural ice most likely to have the highest accumulation rate?

Freezing rain Signup and view all the answers

The presence of ice pellets at the surface indicates what?

There is a temperature inversion with freezing rain at a higher altitude Signup and view all the answers

How does frost on the wings of an airplane affect takeoff performance?

Frost will disrupt the smooth flow of air over the wing, adversely affecting its lifting capability Signup and view all the answers

Why is frost considered hazardous to flight?

Frost spoils the smooth flow of air over the wings, thereby decreasing lifting capability Signup and view all the answers

How does frost affect the lifting surfaces of an airplane during takeoff?

Frost may prevent the airplane from becoming airborne at normal takeoff speed Signup and view all the answers

What conditions result in the formation of frost?

The temperature of the collecting surface is at or below the dewpoint of the adjacent air and the dewpoint is below freezing Signup and view all the answers

An almond or lens-shaped cloud which appears stationary is referred to as?

A lenticular cloud Signup and view all the answers

What are crests of standing mountain waves marked by?

Stationary, lens-shaped clouds known as standing lenticular clouds Signup and view all the answers

When could possible mountain wave turbulence be expected?

When winds of 40 knots or greater blow across a mountain ridge, and the air is stable Signup and view all the answers

Where does wind shear occur?

At all altitudes, in all directions Signup and view all the answers

What wind speed at 2,000 to 4,000 feet above the surface could indicate a wind-shear zone in a temperature inversion?

25 knots Signup and view all the answers

When may hazardous wind shear be expected?

In areas of low-level temperature inversion, frontal zones, and clear air turbulence Signup and view all the answers

What type of weather is most likely to develop if the temperature/dewpoint spread is small and decreasing, with a temperature of 62°F?

Fog or low clouds Signup and view all the answers

What does the term 'dewpoint' refer to?

The temperature to which air must be cooled to become saturated Signup and view all the answers

The amount of water vapor which air can hold depends on what?

Air temperature Signup and view all the answers

What processes add moisture to unsaturated air?

Evaporation and sublimation Signup and view all the answers

What conditions cause clouds, fog, or dew to form?

Water vapor condenses Signup and view all the answers

Low-level turbulence and icing can become hazardous in which type of fog?

Steam fog Signup and view all the answers

In which situation is advection fog most likely to form?

An air mass moving inland from the coast in winter Signup and view all the answers

What situation is most conducive to the formation of radiation fog?

Warm, moist air over low, flatland areas on clear, calm nights Signup and view all the answers

What types of fog depend upon wind in order to exist?

Advection fog and upslope fog Signup and view all the answers

Clouds are divided into four families according to what?

Height range Signup and view all the answers

What does the suffix 'nimbus' used in naming clouds mean?

A rain cloud Signup and view all the answers

What conditions are necessary for the formation of cumulonimbus clouds?

A lifting action and unstable, moist air Signup and view all the answers

Which clouds have the greatest turbulence?

Cumulonimbus Signup and view all the answers

What cloud types indicate convective turbulence?

Towering cumulus clouds Signup and view all the answers

At approximately what altitude AGL can a pilot expect the base of cumuliform clouds if the surface air temperature is 82°F and the dewpoint is 38°F?

10,000 feet AGL Signup and view all the answers

What is the approximate base of the cumulus clouds at 1,000 feet MSL if the surface air temperature is 70°F and the dewpoint is 48°F?

6,000 feet MSL Signup and view all the answers

Cumulus clouds often indicate what?

Possible turbulence Signup and view all the answers

What is a characteristic of stable air?

Stratiform clouds Signup and view all the answers

When warm, moist, stable air flows upslope, what does it produce?

Stratus type clouds Signup and view all the answers

If an unstable air mass is forced upward, what type of clouds can be expected?

Clouds with considerable vertical development and associated turbulence Signup and view all the answers

What are characteristics of unstable air?

Turbulence and good surface visibility Signup and view all the answers

What characteristic is most likely associated with a stable air mass?

Poor surface visibility Signup and view all the answers

Steady precipitation preceding a front indicates what?

Stratiform clouds with little or no turbulence Signup and view all the answers

What are characteristics of a moist, unstable air mass?

Cumuliform clouds and showery precipitation Signup and view all the answers

What measurement can determine the stability of the atmosphere?

Actual lapse rate Signup and view all the answers

What would decrease the stability of an air mass?

Warming from below Signup and view all the answers

What are characteristics of an unstable atmosphere?

A warm, humid air mass Signup and view all the answers

Clouds with extensive vertical development over mountainous terrain are a sign of?

An unstable air mass Signup and view all the answers

The stability of an air mass can usually be determined by what?

Cloud types and the type of precipitation Signup and view all the answers

What feature is associated with a temperature inversion?

A stable layer of air Signup and view all the answers

The most frequent type of ground or surface-based temperature inversion is produced by?

Terrestrial radiation on a clear, relatively still night Signup and view all the answers

When there is a temperature inversion, what would you expect to experience?

An increase in temperature as altitude increases Signup and view all the answers

What weather conditions should be expected beneath a low-level temperature inversion layer when the relative humidity is high?

Smooth air, poor visibility, fog, haze, or low clouds Signup and view all the answers

An increase in temperature with an altitude increase indicates what?

An inversion Signup and view all the answers

Temperature and radiation variations over land with a clear sky lead to?

Minimum temperature occurring after sunrise Signup and view all the answers

Study Notes

Weather Concepts

Physical weather processes involve heat exchange.
Variations in altimeter settings are caused by unequal heating of the Earth's surface, resulting in differing air pressure.

Wind Dynamics

Winds at 5,000 feet AGL can differ from surface winds due to friction with the surface.
At higher altitudes, winds are influenced by the Coriolis force, which deflects winds to the right in the Northern Hemisphere.
Surface winds are generally slower and thus less affected by Coriolis forces.

Icing and Frost

Structural icing in-flight requires the presence of visible moisture.
Highest ice accumulation occurs in freezing rain conditions.
Ice pellets indicate a temperature inversion with freezing rain at higher altitudes.
Frost disrupts airflow over wings, reducing lift and may prevent takeoff at normal speeds.

Cloud Types and Formation

Lenticular clouds are almond-shaped and can indicate strong winds aloft.
Standing lenticular clouds form at crests of mountain waves.
Mountain wave turbulence is likely with winds exceeding 40 knots crossing a ridge in stable air.

Wind Shear

Wind shear can occur at all altitudes and in all directions.
Wind shear zones are common in low-level temperature inversions and frontal zones.

Fog and Humidity

Small and decreasing temperature/dewpoint spreads at 62°F indicate a higher chance of fog or low clouds.
Dewpoint refers to the temperature needed for air saturation.
Water vapor capacity is determined by air temperature.
Processes adding moisture to unsaturated air include evaporation and sublimation.

Types of Fog

Steam fog forms hazardous conditions, particularly with low-level turbulence.
Advection fog forms when a warm air mass moves inland from the coast in winter.
Radiation fog develops in calm, clear conditions over low areas at night.

Cumulus Clouds

Clouds are categorized by height and include stratus and cumulonimbus types, which are linked to stability and turbulence.
Cumulonimbus clouds indicate significant turbulence and convective activity.
Stable air is typically associated with stratiform clouds and poor surface visibility.

Atmospheric Stability

Atmospheric stability can be assessed by analyzing the actual lapse rate, which reflects temperature changes with altitude.
Warming from below decreases stability, while moist air combined with instability is indicated by showery precipitation.
Ground-based temperature inversions occur due to terrestrial radiation, generally on clear nights.

Weather Indicators

Smooth air and poor visibility may be expected under low-level temperature inversions with high humidity.
Increasing temperatures with altitude signal the presence of an inversion layer, influencing weather conditions significantly.

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Test your knowledge of key concepts from Chapter 7 in meteorology. These flashcards cover important terms and definitions related to weather processes and phenomena. Perfect for reviewing essential information before exams.