C05 - Pressure Systems Flashcards
A Low-Pressure system is also known as?
Cyclone.
Low-Pressure systems are characterised by ‘____’ air, it ‘____’ as the surrounding pressure ‘____’ (3)?
- Rising.
- Expands.
- Falls.
The expansion of rising air causes the air to cool and condense which produce what?
Clouds.
True or False. Low Pressures are always accompanied by cloud and precipitation?
True.
True or False. We can expect bad visibility in Low-Pressure areas? Why (2)?
- False.
- We can expect good visibility due to the rising air clearing pollutants and other airborne contaminants from the bottom of the atmosphere.
Name two classification of Low-Pressure systems?
- Deep (intense).
- Shallow (weak).
A deep depression has a ‘____’ number of isobars with a very ‘____’ central value (2)?
- Great.
- Low.
A shallow low has relatively very ‘____’ isobars and a ‘____’ central value (2)?
- Few.
- Higher.
The Coriolis Force deflects air to the ‘____’ in the Northern Hemisphere and to the ‘____’ in the Southern Hemisphere (2)?
- Right.
- Left.
What is Buy Ballot’s Law?
With your back to the wind in the Northern Hemisphere, the Low-Pressure system is to your left.
From 0 ft to 2,000 ft the surface friction counter acts ‘____’?
Coriolis Force.
From 2,000 ft to 5,000 ft the airflow is parallel to the ‘____’?
Isobars.
At what point does the rising air stop at?
Tropopause.
True or False. An area of Low-Pressure at the surface is matched by an area of High-Pressure at Altitude?
True.
When do small scale heat lows occur?
During the day over land masses in the summer.
As Surface Temperature ‘____’, the air ‘____’ and becomes ‘____’. This causes the air to ‘____’ through the Atmosphere by ‘____’ (5)?
- Increases.
- Warms.
- Less Dense.
- Rise.
- Convection.
Vertical Cloud Formations are called ‘____’ and produce ‘____’ (2)?
- Cumuliform Clouds.
- Rain Showers.
What are large scale heat lows?
Many systems around which can reduce the pressure over a large area.
Name two special regions during the summer where large scale heat lows can form?
- North America.
- Asia.
Heat lows generate around the equatorial region to form the ‘____’?
Equatorial Low-Pressure Belt.
True or False. Heat lows migrate towards the Tropic of Cancer and Capricorn depending on the time of the year?
True.
Heat lows have ‘____’ up currents which rise to the Tropopause?
Strong Thermal.
What does the ITCZ stand for?
Inter Tropical Convergence Zone.
What type of weather can be found in ITCZ?
Many isolated by severe Tropical Thunderstorms.
What is a Trough?
An elongated area of Low-Pressure.
Name two types of Troughs?
- Isobaric Trough.
- Trough Line.
What is an Isobaric Trough?
A portion which extends from a Low-Pressure into other system.
What is a Trough Line?
Identified as a solid black line on Synoptic Charts.
What weather can be found on a Trough Line?
Cumulonimbus Clouds with Heavy Showers of Rain/Hail and Strong Wind Gusts.
Low Pressure areas are associated with relatively ‘____’ which flow ‘____’ around the area of Low Pressure in the Northern Hemisphere and ‘____’ in the Southern Hemisphere (3)?
- Strong Winds.
- Anti-clockwise.
- Clockwise.
You can also expect good ‘____’ (except in showers), significant ‘____’ and ‘____’ (3)?
- Visibility.
- Cloud.
- Precipitation.
A High-Pressure system is also known as?
Anticyclone.
In High-Pressure areas the air is ‘____’ and flowing ‘____’ at the surface. The sinking air becomes ‘____’ and its Temperature ‘____’ (4)?
- Subsiding (descending).
- Outwards.
- Compressed.
- Rising.
Subsiding air is very ‘____’ which means ‘____’ cannot form (2)?
- Dry.
- Clouds.
Descending, warming air creates ‘____’?
Subsidence Inversion.
Why is Poor Visibility associated with High Pressure systems?
Due to visible pollutants being trapped beneath the inversion.
Anticyclones have ‘____’ cloud formation which create ‘____’ Temperatures at night (2)?
- Low.
- Low.
In Autumn and Winter around mid-latitudes, ‘____’ can develop in early mornings?
Radiation Fog.
High Pressure areas have a ‘____’ gradient force and so ‘____’ winds exist (2)?
- Weaker.
- Lighter.
True or False. An area of High-Pressure at the surface is matched by an area of Low-Pressure at Altitude?
True.
Coriolis Force causes the airflow to be deflected to the ‘____’ in the Northern Hemisphere. The resultant airflow moves ‘____’ around an Anticyclone (2)?
- Right.
- Clockwise.
Due to surface friction, the flow of surface wind parallel to isobars doesn’t establish itself until above ‘____’?
2,000ft.
Where can Warm Anticyclones be found?
30° Latitude either side of the Equatorial Low-Pressure Belt.
Sub-Tropical Highs are found between which Latitudes?
20° to 40°.
Warm Equatorial Air ‘____’ to the ‘____’, which then ‘____’ becoming more ‘____’ and ‘____’ (5)?
- Rises.
- Tropopause.
- Cools.
- Dense.
- Sinks.
In the Northern Hemisphere, a belt of Polar Front Depression exists at higher latitudes than the belt of Warm Anticyclones. These Depressions move from which direction?
West to East.
During the summer, the Sub-Tropical Highs expend into the Latitude of Polar Front Depressions. Thus, deflecting the Depression in which direction?
Northwards.
True or False. With Cold Anticyclones, patterns of Low Pressure and High Pressure extend North and South of the Equator?
True.
Can High Pressure develop in both Polar Regions? If so, what is the name of this pressure system?
- Yes.
- Cold Anticyclone.
What can be found between the Polar Front Depressions in the mid-latitudes?
Cold Temporary Anticyclones.
Cold Temporary Anticyclones are a consequence of the ‘____’ around them?
Low Pressures.
What is a Ridge?
Extension of a High Pressure Region.
Define the characteristics of a Col in terms of its location?
Found between two High Pressure areas, surrounded by Low Pressure.
Describe the Isobars found in a Col?
Widely spaced.
What are the seasonal weather phenomenon found in Cols (2)?
- Summer = Thunderstorms.
- Winter = Fog.
