Genesis Quiz Flashcards
Why do more tc’S develop in the northern hemisphere
Two additional genesis regions
Large -scale conditions associated with Tc formation
Upper-tropospheric anticyclone outflow; enhanced lower tropospheric relative vorticity; appearance of curved banding features in deep connection;
Falling surface pressure
Greater than or equal to 3mb in a 24 hr period
Tropical waves
Cyclonically curved, produce 70% of Atlantic busin formations
Non-tropical lows and thunderstorm complexes
Frequent precursor of subtropical cyclones which can evolve into Tc, strong upper level divergence
Eddy flow
Turbulent flows develop spinning or swirling structures
Cyclonic wind flow / circulation
North Eddy flow
Superimposed onto the easterly background flow, an open wave instead of closed cyclonic circulation System
Eddy flow + background =
Resultant / combined flow
Why do open tropical waves develop slower than closed lows?
Asymmetrical low-level convergence and convection, convection displaced from lowest pressure axis
What can assist development
Light to moderate easterly deep-layer vertical wind shear, pushes convection/latent heat over wave axis
What direction does most favorable near-zero shear come from
Any direction
_ Tropical waves develop - than - lows due to _
Open; slower; close; asymmetrical low level convergence and convection
What does low / no vertical wind shear do?
Allows vortex column to remain vertical, creating ideal conditions for latent heat released to be concentrated near surface pressure minimum
Unfavorable westerly shear
Greater than 25 kts
Favorable tropical wave shear
Less than 10 kts
Most favorable shear
Okts
Why is a most mid level > 70 % Rh so important in order for Tc genesis to occur
Prevent the development of cold downdrafts created by rain evaporating into dry mid-level air
Entrainment of moist mid level air
Feed convective updrafts with nigh theta -E air, enhances updrafts
Entrainment of dry mid-level air
Creates evaporatively cooled downdrafts, which spread out at the ocean surface, disrupting or even destroying the surface wind field
Dry slot penetration of inner core will
Erode central deep connection & slow down the genesis process
Why do early development of Dolly support Tc genesis?
Merger of mult lower to middle troposphere mesoscale
Ships
Statistical hurricane intensity precipitation scheme
What is the ships model
Statistical - dynamical model that was developed for forecasting the intensity existing tropical cyclones not tropical disturbances
Useful Tc genesis environmental info can be obtained from the
Model output
Madden-julien oscillation
Large scale global gravity wave generated by deep connection that develops and persist over mountainous, elevated heat regions of Asian subcontinent and Asian tropics
Positive phase upper level divergence created
More moist and lower Vws environment
Convectively coupled Kelvin waves
Moderate scale gravity wave generated by deep convective burst
Where do cckw waves develop?
Mountainous, elevated heat regions of Asian subcontinent and tropics
Tc genesis enhanced ahead of cckw due to
Increased upper-level divergence E weakening of low-level easterlies and/or an increase in low level westerlies which increases low level cyclonic vorticity
Cckw is limited to
7 degrees of equator (do not affect Tc genesis at higher lat )
Cckw propagate
Eastward at 15-25 kts
Mjo waves move
Eastward at less than 10 Kts
Since cckws con move slower than, equal to, or faster than the Mjo
Locally de-amplify/degrade or amplify the effects of mjo
Ingredients
Pre existing disturbance, warm sea surface temps, little change in the wind speed and/or direction with height, nigh values of tropospheric moisture, unstable atmosphere, location several degrees latitude away from the equator (coriolisspin)
