Lesson 10 Flashcards
What are synoptic features?
Synoptic features are weather patterns that cover a large area
Wind refers to a horizontal movement of air from an area of low pressure to an area of high pressure (true or false)
FALSE - It moves from high pressure to low pressure`
What does a knot represent as a unit of measure?
One knot is equal to one nautical mile per hour
Isobars are curved lines that connect points of equal pressure and show variations in pressure
at any given time. What is the unit of measurement for an isobar?
Isobars are measured in hectopascals (hPa)
There are 2 basic cloud forms - what are they?
Stratiform or stratus-type clouds which appear in horizontal layers.
Cumuliform or cumulus-type clouds have a more prominent vertical formation and usually do
not cover a large area.
What are the four basic types of cumuliform clouds?
Cumulus (CU)
Towering cumulus (TCU)
Cumulonimbus (CB)
Altocumulus castellanus (ACC)
Name the four types of pressure systems
Pressure systems include high-pressure areas, low-pressure areas, troughs, and ridges.
In what direction will the air flow around a high-pressure system?
Clockwise
What are other names for a high-pressure area?
A high-pressure area may also be called a high or an anticyclone.
In what direction will the air flow around a low pressure system?
Air circulates counter-clockwise around the centre of low-pressure systems
What are other names for a low-pressure area?
A low-pressure area may also be called a low, a cyclone, or a depression.
A trough is associated with a low-pressure system whereas a ridge is associated with a high-pressure system. (True or False)
True
A trough is essentially an elongated region of relatively low atmospheric pressure, often
associated with fronts.
A ridge is essentially an elongated region of relatively high atmospheric pressure.
Define pressure gradient
Pressure gradient is the rate of change of pressure with horizontal distance measured in
kilometres.
Define the Coriolis force
The Coriolis force is caused by the Earth’s rotation.
In the northern hemisphere, as the air moves from a high-pressure area to a low-pressure area, the Coriolis force deflects the moving air to the right. This is because the rotating Earth has a counter-clockwise spin in the northern
hemisphere.
The Coriolis force does not cause wind; it affects the direction of the air movement. Affected air
flows parallel to the isobars. If the Earth didn’t rotate, the wind would flow directly from a high- to
a low-pressure area.
What is Buys Ballot’s law?
According to Buys Ballot’s Law, the wind is at the person’s back, so the
lower pressure is to the left
In the northern hemisphere, the pressure gradient force and the Coriolis force combine to cause
the air to flow parallel to the isobars, clockwise around a high, and counter-clockwise around a
low.
Plainly stated, with the wind at your back in the northern hemisphere, the area of lower pressure
lies to your left.
Veering winds change in which direction
Clockwise - Example: wind is veering from south (180°) to west (270°). The wind direction has changed in a clockwise direction.
Backing winds change in which direction
Counter-clockwise - Example:wind is backing from south (180°) to east (090°). The wind direction has
changed in a counter-clockwise direction.
A lifting agent is a force that pushes air upwards. For clouds and precipitation to occur, air must
be lifted so that it can cool and condense. What are the 5 lifting agents?
- Convection
- Orographic lift
- Frontal lift
- Mechanical turbulence
- Convergence
Define what an air mass is
An air mass is a large section of the troposphere with relatively uniform properties of
temperature and moisture in the horizontal.
What are the 2 types of air masses
- Maritime air masses form over large bodies of water and are humid.
- Continental air masses form over large land areas and are dry.
What are the 3 terms that describe the temperature of air masses
- Arctic air masses are cold and form in the Arctic or at high latitudes.
- Polar air masses are temperate. Despite their name, polar air masses actually form in
the temperate zones (permafrost line to 30°N) by the heating of an Arctic air mass or the
cooling of a tropical air mass. - Tropical air masses are warm and form in the tropics or low latitudes (between 30°N and
the equator).
What are the four air masses commonly found in North America?
Continental Arctic (cA) (in winter only)
* Maritime Arctic (mA)
* Maritime Polar (mP)
* Maritime Tropical (mT)
What is a front?
A front is the transition zone between two air masses.
