what is weather
Weather is the short-term, day-to-day condition of the atmosphere.
� Weather is a "snapshot" of atmospheric conditions.
what is climate
Climate is the long-term average (e.g., over decades) of weather conditions and extremes in a region.
what are the elements contributing to weather
� Temperature � Air pressure � Relative humidity
� Wind speed and direction
� Seasonal factors such as insolation and Sun angle
how do areas on earth effect the characteristics of air in regards to weather?
Each area of Earth's surface imparts its
temperature and moisture characteristics to overlaying air.
The effect of the surface of earth on the air creates what?
regional air masses with a homogeneous mix of temperature, humidity, and stability.
what is an air mass
Air mass is a distinctive body of air with homogeneous mix of temperature, humidity, and stability, and it initially
reflects the characteristics of its source region.
The interactions of air masses produce what?
weather patterns
what are two differences between the air masses of winter vs the air masses of summer in NH?
the air masses of summer has the continental tropical air mass, and the tropical air masses move northward
what is moisture represented by in the classification of air masses
maritime (wet) and continental (dry)
what is temperature represented by in the classification of air masses
A=arctic, P=polar, T=tropical, E for equatorial, AA for antarctic
how are air masses classified
through temperature and moisture
Maritime Tropical from the Pacific characteristics
humid, warm, stable to conditionally unstable
Maritime Tropical from the Gulf of Mexico/Atlantic characteristics
warm, humid, unstable
Continental Tropical (summertime) characteristics
hot, low humidity, stable aloft but unstable at surface, turbulent
Maritime Polar characteristics (Pacific and Atlantic= same)
cool, humid, unstable all year
Continental Polar in the winter
cold, dry, stable, high pressure
Continental Polar in the summer
cold, dry, moderately stable
continental Arctic
very cold, very dry, stable
Density= ?
Mass/volume
RH is relative humidity between
0 and 1
Moist air is _________________________ dense than dry air.
less
Are continental polar air masses only formed in the Northern Hemisphere?
yes
when are continental polar air masses the most developed
in winter and cold-weather conditions
The cold, dense cP air displaces moist and warm air in its path, producing what? (3 things)
lifting, cooling, and condensation
An area covered by cP air in winter experiences what type of weather?
cold, stable air, clear skies, high pressure, and anti-cyclonic wind flow.
Within mP air masses what conditions prevail throughout the year?
cool, moist, unstable conditions prevail throughout the year.
The mT Gulf/Atlantic air mass is unstable and active from what time in the year
late spring to early fall.
What are the differences between the mP tropical in the pacific vs the mP tropical in the atlantic?
The mT Pacific is stable to conditionally unstable and generally lower in moisture content and available energy than the mT Gulf/Atlantic air mass.
lake-effect snowbelts
...
As air masses migrate from source regions, their temperature and moisture characteristics do what?
modify and slowly take on the characteristics of the land over which they pass.
what is an example of this?
lake-effect snow belt of the Great Lakes.
To form precipitation, air masses must do what?
lift and rise in altitude to reach the dew-point temperature, condense, and form clouds.
what are the 4 atmospheric lifting mechanisms
Convergent lifting � Convectional lifting � Orographic lifting � Frontal lifting (cold and warm fronts)
convergent lifting
� Air flows toward an area of low pressure. � Low pressure center: air converging and ascending, cooling and condensation occurring.
convectional lifting
The air above the warmer surfaces is heated and rises. � The warmer surfaces produce convectional lifting due to local heating.
orographic lifting
Oro means "mountain." � Orographic lifting occurs when air is forced to ascend
upslope as it is pushed against a mountain.
Rain shadow
the low-rainfall region that exists on the leeward (downwind) side of a mountain range. This rain shadow is the result of the mountain range's causing precipitation on the windward side.
Explain the processes of air on a mountain
...
frontal lifting
frontal lifting is a form of lifting that results in precipitation as the air rises due to a confrontation between two different types of air
what is a front
A front is the transition zone between two air masses of different densities. Since density differences are most often caused by temperature differences, fronts usually separate air masses with contrasting temperatures.
cold front
The leading edge of a cold air mass is a cold front.
warm front
The leading edge of a
warm air mass is a warm front.
why do cold fronts cause lifting to warm air?
cold fronts are denser
is there more precipitation at cold fronts or warm fronts
cold
why is there more precipitation at cold fronts?
As the front advances, the colder air lifts the warmer air ahead of it (red arrows). The air cools as it rises and the moisture condenses to produce clouds and precipitation ahead of and along the cold front.
what is the behavior of air in a warm front
Warm air moves up and over cold air� Precipitation ahead of the warm front
how do mid latitude cyclonic systems generate
#NAME?
mid latitude cyclonic system
Low-pressure centers converging and ascending air that spirals counter clockwise in the northern hemisphere
Downbursts are associated with
in thunderstorms, turbulence and wind shear
Downbursts are characterized by
Downbursts are characterized by dreaded high-wind-shear conditions that can bring down aircraft.
supercells
The strongest thunderstorms that contain deep, persistently rotating updraft called a mesocyclone.
Heavy rain, large hail, tornadoes may develop
lightning and thunder
-Flash of light caused by enormous electrical discharges (8 million a day on Earth).
-Thunder is the shock wave conveyed by the atmosphere. 90% of all strikes happens on the ground and nearby pointy surfaces
like trees.
hail
Ice pellets larger than 0.5 that form within a
cumulonimbus cloud.
The energy source of thunderstorms is what?
The energy source of thunderstorms is from the condensation of a large amount of water vapor in clouds.
which air mass are thunderstorms associated with?
mT
tornadoes are associated with what?
supercells and squall lines.
how do tornadoes transform from mesocyclones?
As moist air is drawn up into the circulation of a
mesocyclone, energy is liberated by condensation and the rotation of air increases speed.
The narrower the mesocyclone, the __________________ the spin of converging air parcels into the rotation.
faster
when will a tropical storm/cyclone/typhoon be the most powerful
The warmer the ocean and the atmosphere, the more powerful the storm.
where/how does a tropical cyclone originate
Cyclonic motion starts with a slow-moving easterly wave of low pressure in the trade-wind belt of the tropics.
describe the pressure of a mid latitude cyclone
a vast low pressure system
Lake effect snow involves
heavy snowfall on the leeward shores of the great lakes
The Intertropical Convergence Zone is characterized by
warm, wet rising air
Summer afternoon thundershowers in the southeastern United States are more than likely a result of
convectional lifting.
When a cold front approaches, air pressure will initially ________ due to the displacement and uplift of______________
decrease, warm air
After a cold front passes, the temperature ________ and the pressure ________ (relative to the conditions that existed prior to the passage of the front).
decreases, increases
where is a squall line located?
turbulent, changing wind patterns slightly ahead of a cold front
Which of the following is true of migrating centers of low pressure in the Northern Hemisphere?
These pressure systems are characterized by converging, ascending air that spirals inward in a counterclockwise fashion.
The area along a warm front is best described by
warm air being lifted gently and steadily over cooler air
Summer thunderstorms in the southern U.S. are usually produced by towering ________ clouds that form by ________.
cumulonimbus; convection
Hurricanes derive their energy from
the heat of condensation
Uplift and storm development occur on the ________ side of an easterly wave.
western