Weather Flashcards
What is the driving force behind weather
The Sun
What causes the air currents
As solar energy reaches the Earth, equatorial region regions heat up more than the poles, which causes the air there to rise
, drawing air in from cooler areas elsewhere
What creates low pressure
Heated rising air
What creates wind?
Air flowing form areas of higher pressure (cooler with air sinking) to lower pressure areas created when heated air rises
What creates high pressure?
Cooler air falling
Wind is created by air flowing form ______ to _____
highs (high pressure) to lows (lower pressure)
Evaporation
Water vapor rising into the atmosphere
Condensation
The changing of water from a vapor to a liquid
Precipitation
Ay form of water falling from the sky such as rain, sleet, snow, and hail
Barometric pressure
The pressure of the atmosphere
The terms high and low pressure indicate
The pressures relative to the surrounding areas
High and Low Pressures resultfrom
Vertical airflow caused by changed in temperature
Air pressure is measured with
A barometer
Isobars are
Lines of equal pressure
Due to the counterclockwise circulation around low pressure areas in the Northern Hemisphere, cold air will likely be found to the _____ and _____ of low pressure areas
north and west
Due to the counterclockwise circulation around low pressure areas in the Northern Hemisphere, warm air is most often found to the _______ and ____ of low pressure areas
south and east
Define Front
a boundary between two air masses with an abrupt pressure and temperature across it.
Warm Front
red line and half circles
cold front
blue line and triangles
occluded front
purple with half-circles and triangles on the same side
stationary front symbols on a map are
red half circles on one side, blue triangles on the other
What is a cold front?
a warm-cold air boundary with the colder air replacing the warmer denoted on a weather map with a blue line with triangles pointing the direction the cold air is moving
As a cold front moves into an area
the heavier cool air pushes under the lighter, warm air it is replacing
As the warm air rises,
it cools and if the rising air is humid enough, water vapor in it will condense into clouds and maybe precipitation
A Warm Front is
the boundary between warm and cool, or cold, air when the warm air is replacing the cold air
Warm fronts often bring
days of inclement weather
The warm front symbol on a weather map marks
the warm-cold boundary at the Earth’s surface
On a weather map a warm front is indicated by
red half-circles pointing in the direction the warm air is morbing
Where is the warm-cold boundary in a warm front
over the cold air, and can stretch hundreds of miles.
Warm fronts tend to form
to the east of low pressure centers where southerly winds push warm air northward
Occluded front is caused by
A cold front overtaking a warm front
An occluded front is shown on a weather map symbolically as
a line with purple triangles and half circles on the same side
A frontal occlusion often occurs
in the later stages of a storm’s life cycle when the air in the warm sector of the storm is lifted off the ground
A cold occlusion happens when
the air behind the storm front is colder than the air ahead of the storm from. The coldest air undercuts the cool air ahead of the front and the occluded front acts very similar to a cold front
A warm occlusion occurs when
the air behind the front is warmer than the air ahead of the front. The cool air is lighter than the coldest air ahead of the front so the cool air rises up and over the coldest air at the surface and the occluded front acts very similar to a warm front
An occluded front has well-defined
vertical boundaries between the coldest air, the cool air and the warm air
Stationary Front
A cold front is the boundary between cool and warm air when the cool air is replacing the warm. A warm front is the boundary when the warm air is replacing the cold air. When the pushing is a standoff, you have a stationary front.
Stationary front map symbol
combining both the warm front and cold front symbols, you have a line with blue tringles (cold) on one side and red half-circles (warm) on the other
A trough is
An elongated area of low atmospheric pressure that can occur at the Earth’s surface or higher altitudes.
Precipitation tends to fall ___ of the trough axis while _____, ______ air tends to prevail to ________of the trough
east, cooler, drier, west
Air rises ___ of troughs and sinks ____ of troughs
East, Weat
Upper-level troughs influence
many surface weather features, including the movement of surface low pressure areas, clouds and precipitation
A ridge is
an elongated area of high atmospheric pressure
Ridges occur
both at the Earth’s surface and at higher altitudes
Sunny, dry weather usually prevails to the ____ of the upper level ridge while on the ___ of the ridge, wet weather can dominate
east, west
Air tends to ___ east of ridge axis inhibiting clouds and precipitation
sink
air tends to rise to the ____ of the ridge axis, which can lead to the formation of clouds and precipitation
west
Sea breezes form
because water heats up much slower than land. The land heats up, warms the air close to the ground, which rises. Cool air from the ocean moves in to replace the rise warmer air, which may create an on shore wind.
The strength of a sea breeze is relative to
the temperature contrast between the air temperature inland and the ocean temperature
A land breeze is made
by the temperature difference between the quickly cooling land and slowly cooling water. As the land cools, it cools the surrounding air, which moves offshore to replace the warm air over the much more slowly cooling ocean. This is most common during the fall and winter season when water temperatures are still fairly warm and nights are cool
An aneroid barometer reads
atmosphere pressure differences and changes
A barometer that reads rain, change, or clear
tells you nothing
Aneroid barometer shows changes in atmospheric pressure using
a set hand. Tap the face to bring the pointer to the true position. The speed at which the need moves indicates the wind speed. Little or no change indicates that current conditions will continue
Clouds are
masses of small water droplets of tiny ice crystals that float in the air, there are three main types
Cirrus
the highest and are composed entirely of ice crystals. Usually they signal a change in the weather
Cumulus clouds
are heaped and billowy with a “cotton ball” appearance, They will often have flat gray bases, with puffy white topes. Then usually signal good weather, but can produce showers and thunderstorms
Nimbus clouds are
dark rain clouds. Cumulonimbus clouds are large heaps of rain clouds that are often anvil shapes. The are associated with thunderstorms and can produce gusty winds, thunder, rain, hail and lightening.
Stratus clouds are
layered, lowly, dull-colored clouds. The form in layers and usually bring drizzling rain or light-falling snow
Dew point
the temperature at which the air can no longer hold moisture and begins to unload slowly as fond.
Winds are names
from where they blow
Veering winds change
in a clockwise direction, such as a wind changing from north to east
Backing winds change
in a counterclockwise direction. A find changing from the south to from the east would be backing
Apparent wind is
shown on the wind vane of a moving vessel
Apparent wind speed is measure by
an anemometer
Coriolis Effect
Winds are deflected by the Earth’s rotation
The wind pattern that generally influences movement of frontal systems over North America is
the Prevailing westerlies
Fog is
a cloud on the Earth’s surface. It is visible condensations in the atmosphere. Its water or ice particles are smaller than rain or mist and those particles stay suspended in air
Form forms when
air cools to the point (dew point) when water vapor in the air begins to cool into tiny water droplets
fog is more likely to form
at night, and likelier as is gets later and later because the air cooling off more and more
Advection
the horizontal movement of air
Advection fog is created by
warm moist air flowing over cold coastal water. It is very common during winter warming and early spring thaws.
If air is at near moisture saturation, …
moisture will condense out of the cooled air and form fog
Advection fog is worse
When winds are too light to mix the warm humid air near the ground with the cooler drier air above.
Sea smoke
looks like and is sometimes called steam. Cold, dry air blows over warmer water and the water evaporates into the lower layers of the air that is warmed by the water. The warmed air rises and is cooled by the cooler air above enough to for tiny droplets. This is most common in the fall because the cold winds bring cold air over the more slowly cooling warm water.
In the Northern Hemisphere, a wind that shift counterclockwise is a
Veering wind
direction of the surface wind is/are
deflected by the Earth’s rotation
In the Northern Hemisphere, a wind that shifts counterclockwise is a _____.
Backing Wind
A weather forecast states that the wind will commence backing. In the Northern Hemisphere, this would indicate that it will _____.
Shift in a counterclockwise manner
A weather forecast states that the wind will commence veering. In the Northern Hemisphere this indicates that the wind will _____.
Shift in a clockwise manner
A local wind which occurs during the daytime and is caused by the different rates of warming of land and water is a _____.
Sea Breeze
Wind resulting from a land mass cooling more quickly at night than adjacent water is a _____.
Land Breeze
On a weather chart, a warm front is indicated by what symbol?
Line with red half circles on one side
The barometer is an instrument for measuring the _____.
Atmospheric Pressure
Which symbol on a weather chart represents a cold front?
Line with blue triangles
What is the weather chart symbol for an occluded front?
Line with purple half-circles and triangles
A local wind which occurs during the daytime and is caused by the different rates of warming of land and water is a _____.
sea breeze
Prior to reading an aneroid barometer, you should tap the face lightly with your finger to _____.
bring the pointer to its true position
Which symbol on a weather chart represents a Warm front?
Line with red half circles
Which weather chart symbol represents a stationary front?
Line with red circles on one side & blue triangles on the other
A boundary between two air masses is called a _____.
front
