meteorology traditionally involves the study of weather systems, such as - extratropical high and low pressure systems, - jet streams - associated waves - fronts.
the study of convective storms, land–sea breezes, gap winds, and mountain waves
forecasting necessitates understanding a wide range of processes and phenomena acting on a variety of spatial and temporal scales.
forecasting for a coastal location requires information concerning:
- The near-shore water temperature
- The potential for land–sea breeze circulations
- The strength and orientation of the prevailing synoptic-scale wind flow.
The prediction of precipitation type can benefit from knowledge of:
- Atmospheric thermodynamics - Cloud physics.
quasigeostrophic (QG) equations
simplified version of the full primitive equations
- ideal gas
systematic strategy to determine which terms in the equations, often associated with specific physical processes, are most important and which are negligible in a given meteorological setting. By characterizing the temporal and spatial scales associated with specific weather systems, we can systematically neglect “small” terms in the governing equations in the study of those systems.
The length scale
related to the size of a weather system, or how far an air parcel would travel within the system during a given time interval.
The time scale
how long it would take an air parcel to circulate within the system
rawinsonde can measure pressure with
length scale of microscale
time scale of microscale
Example phenomena of microscale
length scale of mesoscale
time scale of mesoscale
1h - 1day
example phenomena of mesoscale
thunderstorm and, land sea breeze
length scale of synoptic scale
time scale of synoptic scale
1 day - 1 week
Example phenomena of synoptic scale
Upper- level troughs, ridges. surface low and high
length scale of planetary scale
time scale of planetary scale
Example phenomena of planetary scale
polar front jet stream, trade winds
what are the variables in the system?
Four independent variables: three spatial directions (x,y,z) and time (t)
a variety of vertical coordinates measures are used in place of the ..........
vertical distance z
a variety of vertical coordinate measures are used in place of the vertical distance z to determine .....
determine position along the vertical coordinate axis
popular choice of vertical coordinates
pressure, sigma (a terrain-following ratio of pressure to surface pressure), potential temperature, or a hybrid among these
the k unit vector maintains
right angles with the horizontal unit vectors.
vertical coordinates are known as......
what is the method pilots use to fly?
aircraft's measure pressure and fly along surfaces of constant pressure
The wind velocity components are based on
the time rate of change in the distance along the respective coordinate axes following the airflow
omega (ω), is defined as
the vertical motion in isobaric coordinates
The pressure-coordinate vertical velocity is negative for .....
upward motion because pressure decrease with height
The Coriolis parameter is related to
the projection of the earth’s rotation onto the vertical (kˆ) axis and is given by f = 2Ωsin ϕ
the earth’s rate of angular rotation, 2π radians day–1 7.292x10−5 rads−1
23 h 56 min
Other basic variables
pressure (p), temperature (T), density (ρ), and specific volume a=1/p
dew point: measure of absolute water vapor content
relative humidity: measure of the degree of saturation
The ideal gas law, or equation of state, provides a useful relation between
the pressure, temperature, and density
virtual temperature Tv= T (1+0.61q)
dry- air gas constant Rd = 287 J/ kg.K