Cyclones/ Fronts Flashcards
What are cyclones?
are low pressure cells
What are the three types of cyclones?
- Mid-Latitude (MLC)
- Tropical
- Tornado
What are the characteristics of all cyclones?
- areas of surface LOW Pressure
- surface convergence of winds
- ascending air
- clouds and PPT
- counterclockwise in N. Hemi, opposite in S
What are the characteristics of anticyclones?
- High Pressure
- descending air
- surface divergence of winds•clockwise flow in N. Hemisphere•clear weather—High and Dry!
Where do air masses form?
- Over oceans
- Large snow surfaces, like Canada & Siberia in winter
- Sometimes over big, dry deserts
What is the flow for cyclones and anticyclones?
Air flows into Low pressure out of High pressure.
What is the flow of cyclones and anticyclones in the northern hemisphere?
In high pressure, anticyclonic divergent clockwise flow
In Low pressure, cyclonic convergent counterclockwise flow
What is the flow of cyclones and anticyclones in the southern hemisphere?
In high pressure, anticyclonic divergent counterclockwise flow
In Low pressure, cyclonic convergent clockwise flow
Where do these cyclones occur?
The two larger phenomena, Tropical and MLCs occur in different places on earth. Tornadoes also occur mainly in the mid-latitudes (and sometimes subtropics)
What are the properties of air masses?
- LARGE -may be>600 mi. across
- nearly UNIFORM air in terms of temperature, moisture, pressure-The air mass is distinct from surrounding air
- The Air mass moves as a UNIT
Where do air masses form and where do they move to?
Are formed in 60 degree latitude and move to equator
What are the four main air mass types?
- cP–continental Polar
- mP–maritime Polar
- cT–continental Tropical
- mT–maritime Tropical
How do the air masses types get their names?
From their source regions! Like winds we name them from where they come
What does the latitudinal position do for air mass types?
Latitudinal Position –determines temp.Polar or Tropical (P or T)
What does underlying surface do for air mass types?
Underlying Surface—Water or Land?–determines the amount of moisture associatedMaritime or Continental (m or c)
What air masses are most important to weather here in blacksburg?
cP and mT
Do air masses mix?
No!
What is a front?
The boundary between air masses
What are fronts a component of?
Mid-latitude cyclones (MLCs)
What are MLCs?
MLCs are areas of low pressure that move across the earth
What is some classic weather associated with fronts?
A –Modified cool air mass. Lowering clouds. Nimbostratus near front, light, steady rain poss. as front approaches, Winds-NE-E-SE
B –Warm air sector (mT). Fair, Humid, Warm/hot
Winds S
C –Cumulonimbus along cold front,Heavy rain, Severe weather possible along the front
D -Cold air sector (cP)Clear, Cool/cold Dry, H press Winds W-N
How does air flow in cyclones and anticyclones?
Look at powerpoint, page 38
What happens in MLCs?
- 3 air masses involved
- Warm front leads
- Warm air rises over cold at both fronts
What is a classic warm front?
Warm air moves into area occupied by cooler air—slides up over cold
What are some characteristics of a classic warm front?
- Note the LOW ANGLE that stretches out clouds far from front
- CIRRUSand LOWERING CLOUDS way out ahead, signal the arriving front
- WIDE BANDsteady precip, STRATUSclouds at front
What is a classic cold front?
FRONTCold air advances into area occupied by warm air—pushes up warmer air, sometimes VIOLENTLY
What are some characteristics of a cold classic cold front?
- Steep slope, rapid movement, passes quickly
- Narrow band of precip, cumulo-type clouds
- sometimes severe weather, T-storms, tornados
What is some classic weather associated with fronts?
A –Modified cool air mass. Lowering clouds. Nimbostratus near front, light, steady rain poss. as front approaches, Winds-NE-E-SE
B –Warm air sector (mT). Fair, Humid, Warm/hot
Winds S
C –Cumulonimbus along cold front,Heavy rain, Severe weather possible along the front
D -Cold air sector (cP)Clear, Cool/cold Dry, H press Winds W-N
What is a classic mid-latitude cyclone?
“comma”shape and heavy cloud cover all around the center of the lowcP
What is the life cycle of a mid-latitude cyclone?
About four days
How does a mid-latitude cyclone begin and end?
Begins with cold front “chasing” warm front. It ends with occluding, cold front (the faster front) catching the warm front.
What does the zone of westerlies do in the n. hemisphere winter?
Zone of Westerlies(belt where ML Cyclones occur) moves equatorwardduring N. Hemi winter
What are special storms?
Onshore flow (NE) of Atlantic moisture meets cold air from H press system
What are some effects of special storms?
- Lots rain
- Lots snow & ice
- HIGH winds-Waves
- Coastal flooding
