JX101/102 Atmosphere Structure and Frontal Mechanics Flashcards
The layer adjacent to the earth’s surface is called the _________.
Troposphere
The atmosphere contains:
___% oxygen
___% Nitrogen
___% Other gas
21% Oxygen
78% Nitrogen
1% Other gas
What is the boundary layer between the Troposphere and Stratosphere?
Tropopause
Occurs at approx 36,000 feet in the United States
What is the standard lapse rate?
2º per 1000 feet
What are the 3 different Environmental (or existing) lapse rates?
Standard (2º C or 3.5º F/1000 ft)
Isothermal (No change)
Inverted (Increase in temp with altitude)
In which atmospheric layer does weather normally occur?
Troposphere
A standard day is defined by \_\_\_in Hg \_\_\_mb \_\_\_Cº \_\_\_Fº
29.92in Hg
1013.2mb
15º C
59º F
Lines of equal pressure depicted on a Surface Analysis Chart are known as ___________
Isobars
If an aircraft flies from an area of higher pressure to lower pressure and fails to update the altimeter setting, what will happen to the actual altitude of the aircraft?
The aircraft will descend and be at a lower altitude
For every ___ºC the temperatures varies from the standard, there will be a __% altitude error
11º C
4% error
What is indicated altitude?
What is read on the altimeter
What is Absolute altitude?
Aircraft altitude above the ground (AGL)
What is True Altitude?
Height above sea level (MSL)
What is Pressure Altitude?
Height above the standard datum plane (29.92in Hg)
What is Density Altitude?
Pressure altitude corrected for nonstandard temperature deviations (indication of aircraft performance)
What is the effect of a strong pressure gradient?
Strong winds
What is the movement pattern of a Low Pressure system?
Upward, inward, counter-clockwise
What causes winds to flow across isobars toward low pressure below 2000 feet?
Ground friction
What is the jet stream?
Narrow band of strong winds, just below the tropopause. Moves at 50 knots or greater.
Wind movement during the day near the ocean and moving toward the land is called what?
Sea Breeze
Air moving away from mountain tops and cooling then settling downward toward the valley floor causing more warm air to be pushed up the mountain is known as a __________
Valley Wind
At night, air sloping down the mountain caused by terrestrial radiation is called a ______ _______
Mountain Wind
Low pressure results from ______ air
Ascending
What is the dew point temperature?
The temperature at which saturation occurs. A direct indication of the amount of moisture in the air.
What is Relative Humidity?
Percent of saturation of the air, or the percentage of water vapor in the air compared to the maximum amount the air could hold.
What is dew point depression?***
Same as dew point spread. How much the air must be cooled to become saturated
What is the difference between Showers and Intermittent precipitation?
Intermittent stops and starts at least ONCE DURING THE HOUR
For clouds to form, moisture in the air to be cooled to the dew point and ________________
Condensation nuclei must be present
The most common form of visible moisture is _________
Clouds
Low clouds have bases that range from _______
Surface to 6500 AGL
Middle cloud ranges from _____ to _______
6,500 AGL to 20,000 AGL
High cloud ranges from _____ to ______
20,000 AGL to 40,000 AGL
What are the 3 forms of precipitation?
Drizzle, Rain, Frozen
What are the four methods by which air masses are lifted?
Convergent (2 masses colliding)
Frontal
Orographic (forced up a mountain)
Thermal
What are the Cloud Type, Turbulence, Visibility, Winds, Precipitation and Icing of STABLE and UNSTABLE Atmosphere?
Stratus, Smooth, Poor, Steady, Steady, Rime
Cumulus, Rough, Good, Gusty, Showery, Clear
What is an air mass?
Large body of air that has essentially uniform TEMPERATURE and MOISTURE conditions in a HORIZONTAL plane
The ______ of an air mass indicates its stability.
temperature
What properties are used to locate and classify fronts?
Temperature, dew point, pressure, wind
What is weather generally behind a cold front?
Rapidly Clearing Skies***
How will the winds shift during a typical cold front passage?
SW to NW
What are the visual indications of an incoming warm front?
Extensive forward slope*** of clouds
How do winds typically shift at a warm front passage?
SE to SW
What type of weather are experienced with a stationary front?
Weather very similar to a warm front
What type of wind shift typically occurs with a stationary front?
180º wind shift
How far ahead of a warm front can the associated cloud system reach?
500 to 700 miles
Where is the worst weather associated with an Occluded front?
From 100 miles south to 300 miles north of the occlusion
What type of wind shift is typically associated with an occluded front?
180º
Every front is located in a _________
Low pressure trough
What is a lapse rate when the temp remains the same with altitude?
Isothermal Lapse Rate
The altimeter setting is corrected for __________.
Sea Level Pressure
What is the average height of the Jet Stream? Average Speed?
30,000 feet
100 to 150 knots
High pressure results from _______ air
Descending
What are the 2 atmosphere cycles?
- Evaporation and Condensation
- Hydrological Cycle
Where do squall lines typically form?
50-300 miles ahead of a cold front?
