meteorology- synoptic systems Flashcards
What is atmospheric pressure due to
the column of air above the point considered and the force of gravity
attracting the air toward the earth.
What does air density vary with
Altitude
50% of the mass of the atmosphere lies below where
5km
What is the unit of pressure
Pascal (Pa)
Meteorologists use what measure of pressure
hectoPascal (hPa)
What is the standard pressure at the surface
1013.25 hPa
Pressure varies directly as what
the density and depth of the fluid causing it
Density of air varies inversely to what
as its temp
Depth may vary due to processes doing what
bringing air to an area or moving away from it
What is the pressure gradient
is the rate of change of pressure with distance, measured perpendicular to the
isobars.
What is an isobar
a line on a weather chart connecting places having the same atmospheric pressure
What is the pressure tendency
is the rate of change of atmospheric pressure with time, standardised as the
change in pressure over three hours
Pressure varies through the day in a regular cycle due what?
to tidal effects caused by heating of the upper atmosphere.
Wind is the horizontal component of what
air movement
What does pgf stand for
pressure gradient force
What is pgf
is the force exerted on air particles due to the pressure gradient at a place.
Any moving body on the surface of a rotating planet experiences a deflection to one side of its direction
of movement except at the
equator
Coriolis Force varies as the sine of latitude from zero at the equator to maximum at the
poles
Coriolis Force acts perpendicularly to the direction of
movement
Coriolis Force acts perpendicularly to the direction of movement, to the ____ of the direction of
movement in the northern hemisphere and to the ____ in the southern hemisphere.
right
left
The magnitude of the coriolis force varies directly as what?
latitude
In low Latitude ________ speed is required to generate the balancing Coriolis Force than in high Latitude.
The speed of the Geostrophic Wind is therefore _______ in low Latitude than in high Latitude for the same Pressure Gradient.
greater
greater
The Gradient Wind is the wind flowing in an area with curved isobars.
Air flowing parallel to curved isobars will follow a curved path.
The force causing the deflection to a curved path is the what?
Centripetal force
Air flowing around an anticyclone must increase speed in order to generate increased Coriolis Force
toward the centre of the system to achieve a what?
curved path
Air flowing around a depression must _________ speed in order to __________ Coriolis Force away from the centre of the system and achieve a curved path.
decrease
decrease
Gradient wind is super-geostrophic where isobars are curved _____________ and sub-geostrophic where
isobars are curved __________.
anticyclonically
cyclonically
The amount of modification of the geostrophic wind speed depends on ________ _________, ________ and
____ _______.
isobar curvature
latitude
wind speed
Friction close to the surface reduces what?
Wind speed
Which reduces coriolis effect
Pressure Gradient Force acts from ____ toward ___ pressure, ____________ to the Isobars.
high
low
perpendicular
What does air move in response to
The pressure gradient force
Coriolis Force deflects flow to the ______ in the Northern Hemisphere, ______ in the Southern Hemisphere,
right
left
Gradient wind describes
flow along curved Isobars, higher than Geostrophic if anticyclonically curved,
lower if cyclonically curved.
Surface Wind flows in toward ___ pressure, crossing the Isobars at the Angle of Indraft.
low
Buys-Ballot’s Law states:
Face the wind.
Lower pressure is to the right in the northern hemisphere (left in the southern hemisphere).
The Angle of Indraft should be taken into account.
The direction of the Pressure Gradient will be 90° plus the Angle of Indraft from the wind direction.
The direction of the centre of low pressure will depend on the isobar pattern.
The Gradient Wind Graph is calculated for Latitude __°.
It is useable over the range __° to __° Latitude
The theoretical maximum anticyclonic gradient wind is twice the geostrophic wind.
50
40
80
The wind speed around anticyclonically curved isobars may be up to ______ the speed that would be
expected from the isobar spacing.
twice
Cyclostrophic wind speed is an approximation to gradient wind speed that ignores, what?
Coriolis force
