NIFE Weather
What is the pressure gradient defined as? - -The rate of pressure change in a direction
perpendicular to the isobars
What type of vertical atmospheric circulation is associated with a low-pressure system? - Air will
ascend (insufficient pressure to keep air at the surface) and try to converge at the center of the low-
pressure, which also produces wind
Define Atmospheric Pressure (Barometric Pressure) - -Pressure exerted on a surface by the
atmosphere due to the weight of the column of air directly above that surface
-Pressure always decreases with altitude (decreases more rapidly at lower altitudes because of
decreasing density)
List some characteristics of the troposphere. - -Adjacent to Earth's surface
-Average height of 36,000'MSL above the US
-Becomes less dense with altitude
-Temperature decreases with increasing altitude
-Nearly all weather occurs here
-Wind velocity increases with altitude
What is the composition of dry air? - 78% nitrogen
21% oxygen
1% mixture of 10 other gases
How much of the atmosphere, by volume, is composed of water? - 0 to 5%
What are condensation nuclei? - -Nongaseous substances such as dust and salt particles, pollen,
etc
,-Water molecules condense on these particles and form clouds
What layer of the atmosphere is adjacent to the Earth's surface? - Troposphere
What is the tropopause and where is it found? - -Transition zone between the troposphere and
stratosphere
-Temperature is constant with altitude
-Jet stream occurs right below (strongest winds)
What are the two units of measurement for atmospheric pressure? - -in-Hg: measure of the
height of a column of mercury that can be supported by atmospheric pressure
-Millibar: direct representation of pressure (force/unit area)
-Normal sea level pressures range from 28-31 in-Hg (960-1060mb)
Surface analysis charts use _______ as the reference pressure level for isobars. - -MSL barometric
pressure (to provide a common reference)
-Allows meteorologists to track weather systems as they move across the country
What type of vertical atmospheric circulation is associated with a high-pressure system? - Air will
descend (downward force exerted by high pressure) and diverge, which produces wind
What effect does the Coriolis Force have on wind as it moves horizontally into/out of high/low pressure
systems? - -Wind will circulate as it moves out of a High-pressure system and into a Low-pressure
system
-Clockwise out of a high-pressure system (in the northern hemisphere)
, -Counterclockwise into a low-pressure system (in the northern hemisphere)
What does the spacing of isobars indicate? - -Rate of pressure change over a horizontal distance
-Closer the spacing, the greater the change
-Pressure Gradient Force
What is the initiating force of all winds? - Pressure Gradient Force
When isobars are close together, the Pressure Gradient Force is ______, and when isobars are far apart,
the Pressure Gradient Force is _______________. - greater/steeper
more shallow/weaker
What are the conditions of a standard day? - -29.92 in-Hg (1013.2mb)
-15 deg C (59F)
-Standard day conditions at sea level
What is the standard lapse rate for pressure and temperature? - -A 1,000' increase in altitude will
cause.....
Pressure to decrease by 1.0 in-Hg (34mb)
Temperature to decrease by 2 deg C (3.57F)
What is an isothermal lapse rate and where can it be found? A thermal inversion lapse rate? - -
Isothermal: temperature remains the same for different altitudes (tropopause)
-Inversion: temperature increases with altitude (stratosphere)
What is an air mass? - -A large body of air that has essentially uniform temperature and moisture
conditions in a horizontal plane
-No abrupt temperature/dew point changes at a given altitude
-Named according to their location, moisture content, and temperature
What is the pressure gradient defined as? - -The rate of pressure change in a direction
perpendicular to the isobars
What type of vertical atmospheric circulation is associated with a low-pressure system? - Air will
ascend (insufficient pressure to keep air at the surface) and try to converge at the center of the low-
pressure, which also produces wind
Define Atmospheric Pressure (Barometric Pressure) - -Pressure exerted on a surface by the
atmosphere due to the weight of the column of air directly above that surface
-Pressure always decreases with altitude (decreases more rapidly at lower altitudes because of
decreasing density)
List some characteristics of the troposphere. - -Adjacent to Earth's surface
-Average height of 36,000'MSL above the US
-Becomes less dense with altitude
-Temperature decreases with increasing altitude
-Nearly all weather occurs here
-Wind velocity increases with altitude
What is the composition of dry air? - 78% nitrogen
21% oxygen
1% mixture of 10 other gases
How much of the atmosphere, by volume, is composed of water? - 0 to 5%
What are condensation nuclei? - -Nongaseous substances such as dust and salt particles, pollen,
etc
,-Water molecules condense on these particles and form clouds
What layer of the atmosphere is adjacent to the Earth's surface? - Troposphere
What is the tropopause and where is it found? - -Transition zone between the troposphere and
stratosphere
-Temperature is constant with altitude
-Jet stream occurs right below (strongest winds)
What are the two units of measurement for atmospheric pressure? - -in-Hg: measure of the
height of a column of mercury that can be supported by atmospheric pressure
-Millibar: direct representation of pressure (force/unit area)
-Normal sea level pressures range from 28-31 in-Hg (960-1060mb)
Surface analysis charts use _______ as the reference pressure level for isobars. - -MSL barometric
pressure (to provide a common reference)
-Allows meteorologists to track weather systems as they move across the country
What type of vertical atmospheric circulation is associated with a high-pressure system? - Air will
descend (downward force exerted by high pressure) and diverge, which produces wind
What effect does the Coriolis Force have on wind as it moves horizontally into/out of high/low pressure
systems? - -Wind will circulate as it moves out of a High-pressure system and into a Low-pressure
system
-Clockwise out of a high-pressure system (in the northern hemisphere)
, -Counterclockwise into a low-pressure system (in the northern hemisphere)
What does the spacing of isobars indicate? - -Rate of pressure change over a horizontal distance
-Closer the spacing, the greater the change
-Pressure Gradient Force
What is the initiating force of all winds? - Pressure Gradient Force
When isobars are close together, the Pressure Gradient Force is ______, and when isobars are far apart,
the Pressure Gradient Force is _______________. - greater/steeper
more shallow/weaker
What are the conditions of a standard day? - -29.92 in-Hg (1013.2mb)
-15 deg C (59F)
-Standard day conditions at sea level
What is the standard lapse rate for pressure and temperature? - -A 1,000' increase in altitude will
cause.....
Pressure to decrease by 1.0 in-Hg (34mb)
Temperature to decrease by 2 deg C (3.57F)
What is an isothermal lapse rate and where can it be found? A thermal inversion lapse rate? - -
Isothermal: temperature remains the same for different altitudes (tropopause)
-Inversion: temperature increases with altitude (stratosphere)
What is an air mass? - -A large body of air that has essentially uniform temperature and moisture
conditions in a horizontal plane
-No abrupt temperature/dew point changes at a given altitude
-Named according to their location, moisture content, and temperature
