Storms 4 Flashcards
Where are mammatus clouds
underside of thunderstorm anvil
What are winds
air motions
or air-parcel movement
Moisture Advection
wind blowing in warm, humid air (storm fuel)
Storms can become organized due to
moisture advection
-> positive feedback
-> longer-lasting storms
Radiative heat from the sun causes (what does sensible and latent heat do)
sensible: air gets warmer
latent: humidity rises
What creates winds
forces
acceleration formula
(Vnew - Vold) ÷ ∆t
Prognostic equation / “forecast method” for wind
Vnew = Vold + [ (F/m) x ∆ t ]
Air parcel is
hypothetical blob of air
- size of city block
Buoyancy force
vertical
causes up and downdrafts
Pressure-gradient force (PGF)
horizontal OR vertical
drives horizontal winds
How does temperature alter buoyancy to drive vertical winds?
Temp -> density -> buoyancy
warm air rises (updraft)
cold air sinks (downdraft)
Buoyancy of an air parcel depends on the DIFFERENCE btwn ___ & ___
parcel temp and surrounding air temp
What is the driving force of storms?
Buoyancy
What processes drives the violent updrafts in Tstorms?
- Condensation in storms release latent heat
- latent heat warms the air, making it buoyant / rise
Pressure equation and units
Force / Area
N / m^2
True or false: pressure drives winds
true
Pressure gradient is
pressure DIFFERENCE across a distance
(air moves to lower pressure region)
force uses ∆ p, the diff btwn opposing pressures
What is in the core of a hurricane? How does this make the core warmer?
lots of thunderstorms
-> condensation in these storms makes the core warmer
Summary of how pressure gradients drive horizontal winds
Review slides for explanation
Horizontal changes in temp
-> Horizontal changes in pressure (High pressure at top, Low at bottom)
-> pressure gradient increases at higher altitudes
-> drives faster winds at higher heights
What type of force drives the violent winds in hurricanes? (and also atmospheric rivers)
Pressure-gradient force
What are atmospheric rivers and how do they pose a danger?
flowing streams of water vapour
-> when air hits mountains, it is forced to rise
-> air cools at adiabatic lapse rate (10C/km)
-> causes water vapour to condense = rain + flooding
Continuity concept
(Assuming at the same temperature)
Air molecules tend to spread smoothly and evenly
- no gaps, don’t get bunched together
What does continuity cause?
circulations
What is circulation? Describe how it happens
when initial vertical motion (due to buoyancy) generates horizontal motion in surrounding air
(keeps going)
- buoyant air rises, leaves a room of low pressure below it
- surrounding air sucked in to fill hole to maintain continuity
- air above rising parcel is compressed, expands horizontally
Circulations can be driven by
Buoyancy or horizontal pressure-gradients
Continuity effect links ____ into ____
vertical and horizontal winds into circulations
Hail falls when they are
heavy enough to oppose the updraft
Hail safety
safety glasses
drive away
stay under a roof, etc
What place is most at risk of hail?
Red Deer, Alberta
What forces does temperature alter
buoyancy and PGF
Rain Hazards Summary
- can be heavy
- cover small area
- transient (lasts for short amount of time)
- moves with storm
- flash floods & trigger land slides
- reduced visibility
- move to high ground
Hail Hazards Summary
- can come from any large Tstorm
- most common with supercells (low precipitation)
- injury or death
- dent cars, break windows
- flatten crops within minutes, kill livestock
- get indoors, leave, go under a roof
- safety glasses
True or false: storms of the same type have the same hazards
False
diff storms behave differently, so they don’t all have the same hazards!
Mammatus clouds on the underside of anvils usually happen near
sunset
Hail is most common with what type of Tstorm?
Supercells (low precipitation)
True or false: a larger buoyancy implies a greater vertical acceleration
True
True or false: a warm air parcel will not want to rise if the surrounding air is warmer
True
What would happen if air molecules are removed from a hurricane core?
the hurricane strengthens
