Whether the Weather- chapter 1 Flashcards

1
Q

Troposphere:

Altitude

What’s so special about it?

A

The troposphere is where nearly all weather occurs

large amounts of moisture and increased winds

altitude: 28k-55k AGL (36k AGL over US)

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2
Q

Define:

Atmospheric Pressure

A

The weight of a column of air directly above an area on the earth’s surface

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3
Q

What are the standard units of pressure measurement?

A

Standard units of pressure measurement:

inches of Mercury (Hg)

Millibars (mb- this is used internationally)

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4
Q

What is a pressure gradient?

A

pressure gradient is a change in pressure

Pressure Gradient Force is the pressure exerted on the surfaces of the earth

high pressure is the result of descending air

low pressure is the result of ascending air

*remember: air moves from areas of higher pressure to areas of lower pressure

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5
Q

Define:

Pressure Lapse Rate

what is the standard pressure lapse rate?

A

Pressure Lapse Rate is the decrease in inches of Hg with an increase in altitude

Standard Pressure Lapse Rate:

1” lost per 1,000’ altitude gained

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6
Q

What is the average temperature lapse rate in degrees Celsius?

A

2ºC per 1000’ altitude gained

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7
Q

Define:

Standard Atmosphere

A

Standared Atmosphere:

29.92” Hg

15°C

Temperature Lapse rate: 2C per 1000’f

Pressure lapse rate: 1” Hg/1000’

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8
Q

What is the difference between sea level pressure and station pressure?

A

Station Pressure is the atmospheric pressure read directly at an airfield or specific altitude,

Sea Level Pressure = station pressure + field elevation

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9
Q

What is Indicated Altitude?

A

Indicated Altitude is what the altimiter says

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10
Q

What is the effect of pressure change on an altimeter?

A

A change of 1” Hg will change the altimeter reading by 1,000’

“High to low: Look out Below” means your plane is descending

“Low to High: plenty of Sky”- means your plane is ascending

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11
Q

What are the effects of temperature deviations from the standard lapse rate on the altimeter?

What if its colder than standard conditions?

warmer than standard conditions?

A

Temperature has a minimal effect on altimeters except at extreme temps.

For completion:

if its colder than the standard atmosphere (15C) the altimeter will indicate a higher altitude

if its warmer than the standard atmosphere, the altimiter will indicate a lower altitude

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12
Q

Define:

Air Mass

A

An air mass is a large body of air with relatively the same temperature and moisture characteristics across a horizontal plane

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13
Q

Define:

Saturation

A

Saturation happens when the air can’t hold any more moisture

temperature = dew point

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14
Q

Define:

Dew point temperature and depression

A

dew point temperature is when air reaches a state where it can hold no more moisture

the dew point “spread” or depression is the difference between temperature and dew point. This means that Saturation happens when the spread is 0.

*As the dew point spread decreases, moisture becomes visible as fog, rain, mist, etc.

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15
Q

Why does atmospheric circulation occur?

A

Wind Circulation occurs because of the heating and cooling of the earth which leads to ascending and descending air. Top it off with the spinning of the earth (coriolis effect) and you’ve got yourself some circulation

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16
Q

Define:

Temperature inversion

A

An inversion happens when some circumstances causes the temperature to increase as you gain altitude

17
Q

Define:

Relative humidity

A

Relative Humidity:

its not a direct measurement of the actual water/vapor moisture in the air. Its a measurement of the actual amount of moisture compared to the total amount that COULD be present

18
Q

What is the composition of the Atmosphere?

A

78% Nitrogen

21% Oxygen

1% a combo of 10 other gasses

19
Q

What is True Altitude?

A

True Altitude:

height above MSL

*this is the standard used around the world

20
Q

Define:

Absolute Altitude

A

AGL is height above the terrain

21
Q

Define:

Density altitude:

A

density altitude is not displayed

its a calculation to determine the altitude that the airplane “thinks” its at

gauges performance

22
Q

Define:

Pressure Altitude

A

Pressure Altitude:

the altitude displayed withn 29.92 is set in the kollsman window

its the standard altimeter setting in class A airspace

23
Q

How is an air mass named?

A

An air mass is named for its temperature relative to the SURFACE

*Cold air masses = unstable

*Warm air masses = stable

24
Q

What happens if the setting in the kollsman window is incorrect?

A

The indicated altitude will never match the true altitude whenever the setting in the kollsman window is incorrect