Weather: Synoptic Features

a synoptic feature is a weather pattern that covers a large area

True

The two basic cloud forms are _______ and _______

Stratifrom (stratus-type), Cumuliform (cumulus type)

Stratus-type clouds appear in ______ layers and often have very small ______ motions associated with them

horizontal, vertical

Cumulus type clouds have a more prominent _______ formation and usually _____ cover a large area

vertical, do not

cumulus type clouds are a result of rising air currents and have significant ______ and ________

updrafts, downdrafts

there are ____ types of cumuliform clouds

4

the four types of cumuliform clouds are:

Cumulus (CU), Towering Cumulus (TCU), Cumulonimbus (CB) and Altocumulus Castellanus (ACC)

All of the following are features of Cumulus clouds (CU) except:

• they develop vertically in the form of rising mounds, domes, or towers

• have a bulging upper part

• appear detaches from other clouds

• their height exceeds their width

• generally dense with sharp or ragged outlines

• mostly brilliant white at the top and their bases are relatively dark and nearly horizontal

their height exceeds their width

Towering Cumulus (TCU) are also know as cumulus congestus

True

All of the following are features of TCUs EXCEPT:

• are made up of rapidly growing cumulus or individual dome-shaped clouds

• the height of a TCU exceeds the width

• they have a distinctive cauliflower top that often means showers below

• they contain thunderstorm activity

they contain thunderstorm activity

CB’s are thunderclouds

True

Which of the following is NOT a feature of a CB

• they contain thunderstorm activity

• appear heavy and dense with a considerable vertical extent in the form of a mountain or huge tower

• they contain patches, sheets, layers of clouds, generally with shading

• at least part of a CB’s upper portion is smooth, fibrous, or striated, and nearly always flattened (anvil shape or plume)

• low ragged clouds frequently occurs under the base

they contain patches, sheets, layers of clouds, generally with shading

ACC’s are white, grey, or both white and grey

True

ACCs are composed of laminae, rounded masses and rolls, which are sometimes partly fibrous or diffuse, and which may or may not be merged

True

CBs can attain heights of more than ______ but most CBs in Canada average about ________

70,000ft, 39,000ft

ACCs are often a telltale sign of impending _______ development

thunderstorm

Pressure systems include _____, ______, ______, and _______

high pressure areas, low pressure areas, troughs, ridges

A region where the atmospheric pressure is greater than its surrounding environment is known as a

High pressure area

In a high pressure area, pressure values _______ towards the center

increase

A high pressure area may also be called a high or anticyclone

True

Air circulutes _____ around the center of a high-pressure system and are represented by _____ on surface weather maps

clockwise, H

A region where the atmospheric pressure is lower than its surrounding environment is known as a

low pressure area

Pressure values _____ towards the center of a low pressure area

decrease

A low pressure area may also be called a ______, ______, or ________

low, cyclone, depression

Air circulates _____ around the center of a low-pressure area, and they are labelled as ____ on surface weather maps

counter-clockwise, L

arms extending from a low pressure system are called

troughs

arms extending from the center of a high pressure system are called

ridges

______ are used to represent different pressure systems on weather maps

isobars

Isobars join lines of equal _____ and form pressure patterns that outline or enclose high and low pressure areas

mean sea level pressure (MSLP)

Which of the following is NOT true regarding isobars

• they are measured in hectopascals

• analyzed on meteorological charts

• used to identify high and low pressure systems

• spaced every 10 hPa above and below 1000 hPa

spaced every 10 hPa above and below 1000 hPa

______ is the rate of change of pressure with horizontal distance measured in KM’s

Pressure Gradient

with pressure gradients, the speed of wind is ______ to the pressure gradient, meaning the faster the pressure changes, the ______ the wind will be

directly proportional, stronger

when Isobars are widely spaced or far apart, this indicates a

weak pressure gradient

when isobars are close or crowded together, this indicates a

steep pressure gradient

Air moves from areas of _______ towards areas of ______, but not directly

high pressure , low pressure

Which of the following about the Coriolis Force is NOT true

• It aeffects the direction of air movement

• it does not cause wind

• affected air flows parallel to the isobars

• it deflects moving air to the left in the norther hemisphere and to the right in the southern hemisphere

it deflects moving air to the left in the norther hemisphere and to the right in the southern hemisphere

Buys Ballots Law states that in the northern hemisphere, the pressure gradient force and the Coriolis force to combine to cause the air to flow parallel to the isobars _______ around a high, and ________ around a low

clockwise, counter-clockwise

Buys Ballot’s Law plainly states that in the _______ the area of lower pressure lies to your ________

northern hemisphere, left

_____ is when the wind makes a clockwise change in direction

Veering

Backing is when the wind makes a _______ change in direction

counter-clockwise

The wind has moved in a clockwise direction from South (180°) to West (270°). This is an example of

Veering

Friction at the surface and up to about 3,000ft causes the wind to:

slow down, flow into a low pressure area, flow out of a high pressure area

_____ are used to represent wind formation on surface maps

Arrows

The arrow for wind is always plotted to indicate the direction the wind is blowing from

True

Every arrow has barbs at one end that indicate wind ______. Each full barb is ______ and each half barb is ______

speed, 10 kts, 5 kts

A _____ is a force that pushes air upwards

Lifting Agent

There are _____ lifting agents

5

The five lifting agents are:

convection, orographic lift, mechanical turbulence, frontal lift, convergence

With _____, air is heated from below by contact with the Earth’s surface

Convection

With _____, air is forced up slopping terrain by the wind, and the type of cloud that results depends on the stability of the lifted air

Orographic Lift

With _______, air is forced to rise by a wedge of colder or denser air

Frontal Lift

A cold front is advancing cold air that undercuts the warm air

True

A warm front is defined as cold air that ______ and gives way to the hot air which is less dense and slides over the cold air

retreats

Mechanical turbulence is friction between the air and ground that causes the air to be stirred up into a series of swirling motion known as

eddies

Mechanical turbulence does NOT depend on the strength of the wind and roughness of the terrain

False

Convergence occurs at the centre of ________ systems where the air converges at a point and is forced to rise, resulting in cloud and precipitation

low pressure

A _____ is a large section of the troposphere with relatively uniform properties of temperature and mositure in the horizontal

Air Masses

An air mass takes on it’s original properties from the surface over which it has formed

True

The pressure within any given air mass does not vary considerably

False

All air masses are described by both ______ and ______

humidity, temperature

There are two types of air masses: ______ and ______

maritime air masses, continental air masses

There are three terms to describe the temperature of air masses in america. They are:

Arctic, Polar, Tropical

The four air masses commonly found in North America. They are

Continental Arctic (cA), Maritime Arctic (mA), Maritime Polar (mP), Maritime Tropical (mT)

_____ is the transition zone between two air masses

front

Since North America has four air mass structures, there are three frontal boundaries

True

A cold front is a transition zone between _______ cold air and warm air

advancing

A warm front is a transition zone between warm air and _______ cold air

retreating

A transition zone between two air masses that are not moving is called a

Stationary Front

Arrowheads are used on a weather map to identify a

cold front

Half-circles are used on a weather map to identify a

warm front

A stationary front is identified on a weather map by

alternating arrowheads and half-circles

At a front, the colder air acts as an inclined plane that forces the warmer air to _______

rise

Severity of the weather created by a front depends on several factors. Which of the following is NOT a factor

• slope of the frontal surface

• type of cloud formed

• speed of the frontal movement

• temperature of the lifted air mass

• moisture content of the lifted air mass

• stability of the lifted air mass

type of cloud formed

High pressure is generally associated with ______ weather

Nice

Ridges tend to bring ______ and _____ weather since air is often sinking with a ridge

warmer, drier

Before a cold front arrives, the wind ahead of the front is typically out of the south-southwest. Once the front passes through, the wind usually veers around to the west-northwest

True

A sudden change in wind _____ is common with the passge of a front. On the ground, the wind shift usually occurs ______ the front

direction, at the

Passage of a warmer front will result in an increase in temperature that may ______ the front reaches the station

begin before

Arrival of a cold front will generally result in a sudden _____ in surface temperature

Decrease

It may be possible that it may be many hours after the frontal passage before temperatures drop to the true value of the cold air mass

True

With the passage of a cold front, you may see a small temperature increase for a short period of time after the frontal passage

True

Dew Point temperatures generally _______ with a warm frontal passage

increase

Dew Point temperatures generally _____ with a cold frontal passage

decrease

Dew temperature can never be ________ air temperature

higher than

Visibility is NOT reduced well in advance of warm fronts

False

Precipitation that does not reach the ground is called

Virga

Ahead of cold fronts, visibility is generally ____

good

Fronts are generally associated with areas of ______ pressure

low

Frontal Turbulence is caused by a lifting of _____ air by a frontal surface leading to instability or abrupt shifts in wind direction and speed between the warm and cold air masses near the frontal surface

warm

Frontal turbulence is strongest when the lifted warm air is ______ and ______

moist, unstable

Most severe cases of frontal turbulence are generally associated with fast-moving ______ fronts

cold

At a warm front, ______ factors will determine the cloud type and precipitation

3

The three factors that determine the type of cloud and precipitation at a warm front are _______, ________, _________

moisture content of the overrunning warm air, stability of the overrunning warm air, degree of overrunning

Which of the following is NOT one of the three factors that determine the type of cloud and precipitation at a cold front are

• moisture content of the lifted warm air

• moisture content of the overrunning warm air

• stability of the lifted warm air

• degree of lift

moisture content of the overrunning warm air