Low Pressure System Flashcards
In the NH, which way does win flow in a low pressure system
ANTI CLOCKWISE
In a low pressure system, air is usually STABLE or UNSTABLE
UNSTABLE
Which front moves faster, COLD or WARM
COLD
When warm air pushes into cold air, this is known as what
WARM FRONT
When cold air pushes into warmer air, this is known as what
COLD FRONT
What is an occluded front
Where cold and warm air fronts join together
What are the 2 types of occluded fronts
- COLD
- WARM
What is the definition of a cold occlusion
Cold Air catches up to cool air
Cold air may not be as cold as the front ahead of it
What is the definition of a warm occlusion
Cool air catches up to cold air
What are the areas between fronts known as
SECTORS
Describe the key characteristics of a warm sector
- Area of warmer air behind a warm front
- Between warm and cold fronts
- In a depression
Describe the key characteristics of a cold sector
- Area of colder air immediately behind a cold front
- Between cold and warm fronts
- In a depression
Describe the key characteristics of a cool sector
- Area immediately ahead of a warm front
- Caused by mixing of warm and cold air
- Cold air comes from the cold front ahead of the warm front
What are the 3 sectors of fronts
What order are they typically in
- Warm Sector
- Cool Sector
- Cold Sector
Warm Sector –> Behind cool sector –> Behind Cold Sector –> Behind a warm sector
What is the slope ratio if a warm front
1:150
What is the typical spread (distance) of a warm front
500nm
How is a warm front formed
Warm air rises up colder air
Why do warm fronts typically form clouds
As air rises it cools
Relative himidty increases
Condensation occurs
what are 4 characteristics of the passing of a warm front;
1. Wind
2. Pressure
3. Temperature and dew point
4. Rain
- Surface wind veers
- Pressure steadies then decreases
- Temperature and dew point increase
- Precipitation decreases
What happens to warm air as the cold front approaches
- Forced to Rise
- Cools and condenses
What type of rain fall can be expected with a cold front
Over what time frame
- Sharp showers
- Heavy rainfall
- Short period of time
What cloud type might be present 500nm ahead of a cold front
CIRRUS
CI
What cloud type might be present 200nm ahead of a cold front
Cumulus
CU
Wind VEERS or BACKS with the passing of a front
VEERS
What are 5 characteristics of the passing of a cold front;
1. Surface wind
2. Pressure
3. Temperature and dew point
4. Cloud
5. Weather and visibility
- Surface wind veers sharply (Gusting)
- Pressure low, then sudden increase
- Temperature and Dew point drop sharply
- Patchy low cloud behind front
- Abrupt weather change to fine and good visibility
Warm fronts travel at what speeds compared to cold fronts
2/3 the speed
Occluded front 2 characteristics
- Air touching ground associated with “cold” sector
- End of depression
What is a trough of low pressure
CONCENTRATED LOW PRESSURE
Squeezed between two high pressure systems
Close isobars
Severe weather, increased mixing & lifting
A danger of squall lines to a pilot
No easy way around them
