chapter 4 Flashcards
mesoscale circulation in tropics:
Diurnal variation of solar radiation and temperature are greater than annual variation
mesoscale circulation in mid lat:
annual variation is greater than diurnal variation
what causes land and sea breeze and mountain circulation
- land and sea boundaries and topography
- cause differential diurnal heating
- more pronounced in the tropics
- initiate
- mesoscale circulation
- land sea breeze
- mountain circulation
- mesoscale circulation
- cause differential diurnal heating
from sea to land is called
land breeze
Land sea breeze
- Difference in land sea breeze extend between tropics and mid lat
land sea breeze is due to
- weaker corriolis acceleration in the tropics
- can be explained by using rossby radius of deformation
rossby radius of deformation is a measure of
- the effect of corriolis parameter (earth rotation) on circulation
- the ratio of gravity wave speed (c) to the corriolis parameter (f)
L=c/f = sqrt(gH)/2(omega)sin(o|)
H is …….. and is proportional to …………….
equivelent depth
- stability
- the acceleration due to gravity
……….. and ………. change from mid latitude to tropics
only H and o|
Range of H in tropics:
(10-500m) 400 m > the value of H in mid lat (by order of 1 mag)
compare Lr in tropics and midlatitude
- large in tropics
- H is greater
- o| is smaller
- small in mid lat
- H is smaller
- o| is larger
calculate Lr where H is 400 m assume f=10-5 s-1
6300 km (radius of deformation)
radius of deformation
if circulation smaller than the calculated value the corriolis have no effect
tropics circulation ……………. than the radius of deformation ………………….
smaller
are not effected by that circulation
Mid latitude circulation ……………. than the radius of deformation ………………….
is larger
limits the horizontal extent of the land sea breeze by turning the wind and thus limiting its inland or offshore influence
what is mountain valley circulation
thermally forced circulation
land sea circulation and mountain valley circulation is due to
- Land sea circulation:
- due to differential heating induced by land water distribution (differences)
- mountain valley circulation:
- due to differential heating induced by elevation differences
Mountain valley circulation types
- upslope breeze (valley breeze)
- downslope breeze (mountain breeze)
valley breeze (upslope)
- occur in after noon (as the solar radiation heats the surface)
- give rise to cloudiness over mountains
- maximum rainfall at around 1000 m above the valley floor
- rainfall decreases at teh foot or toward the top of the mountain (due to evaporation)
mountain breeze (downslope breeze)
- occur at night
- clear sky over the mountains
where convective clouds dominate:
- Rain fall is maximum at 1000m (convective clouds)
- rain fall decrease:
- above: lack of moisture
- below:
- dont experience much orographic lift
- evaporation of rain bellow the cloud base
where stratiform cloud dominate the maximum rainfall tend to occur near the top of the mountain
Stress differential:
air flowing parallel to a coastline is subjected to more drag by land than by the sea due to abrupt change in friction
cross isobaric angle large and small (graphs)
the cross isobaric angel from o|
o|= CD/F
CD: drag coef
F: corriolis parameter
o| depend on:
- cp: if Cd is more -> larger o|
- f: if f is small (low lat) –> larger o|
the two sinarios where low is once to the right and once to the left (graph)
Coastal influence in summer: (graph)
- stress differential (and induced div) overland
- increase temperature gradient between land and sea which
- strengthen summer monsoon circulation
- increase temperature gradient between land and sea which
