PHAK Ch 12 Weather Theory Flashcards
What is the composition of the Atmosphere?
78% Nitrogen
21% Oxygen
1% Argon, CO2, and trace gases
What is the Tropopause?
-Boundary between Troposphere and Stratosphere.
-Associated with the location of the jet stream and potential clear air turbulence.
What is the Troposphere?
Lowest layer of the atmosphere
-6 to 20 km (4 to 12 miles) thick over poles.
-Up to 48,000’ (14.5 km) thick over equator.
-Most weather, clouds, storms, and temperature variations happen in this layer.
-Temperature decreases 2*C per 1000’.
-Pressure decreases 1 inHg per 1000’.
What are the layers of the Atmosphere?
—Space—
-Exosphere
-Thermosphere
-Mesosphere
-Stratosphere
-Troposphere
—Earth—
What is the Stratosphere?
-Extends from Tropopause to 160,000 ft.
-Very little weather, occasional clouds.
What causes atmospheric circulation?
-Uneven heating of the Earth’s surface.
-The Earth’s rotation
Why does warm air rise and cool air sink?
The molecules in warm air spread apart, making it less dense. The molecules in cool air contract, making it more dense.
How does air circulate across the planet?
In the Northern Hemisphere:
-Warm air rises and moves North. Due to the Coriolis Effect, the air mass will deflect more and more to the East until it cools, sinks, and begins moving South again. This cycle happens in three cells, between 0* and 30, between 30 and 60, and between 60 and North Pole.
Why do equatorial regions receive more solar heating?
Equatorial regions receive more sunlight that regions farther from the equator.
What affects atmospheric air pressure?
-Temperature: Warmer = Lower pressure.
-Altitude: Higher = Lower pressure.
-Density: High or low pressure systems.
What does the Coriolis Effect do?
In the Northern Hemisphere:
It causes the warm air mass moving northward to deflect to the right (East), causing it to follow a curving path instead of a straight line.
How does the Coriolis Effect change with Latitude?
-The air deflection is greatest at the Equator, and drops to zero at the poles.
What is standard sea level barometric pressure?
-29.92 inHg at 59* F (15* C)
-1,013.2 mb at 59* F (15* C)
What is the conversion of inHg to mb?
1 inHg = aprox 34 mb.
How do non-sea level weather stations report barometric pressure?
They convert to sea level pressure by adding 1 inHg for every 1000’ of elevation. For example, a station at 5000’ seeing 24.92 inHg will report 29.92 inHg.
