Chapter 13) Lesson 2 Weather Patterns Flashcards
study for quiz on ____
What is a high-pressure system?
a high pressure system is a large body of circulating air with high pressure at its center and lower pressure on the outside of the system.
What happens in a high pressure system?
The air on the inside of the system moves away from the center. dense air sinks, bringing clear skies and fair weather.
What is a low-pressure system?
a low-pressure system is a large body of circulating air with low pressure at its center and higher pressure outside of the system.
What happens in a low-pressure system?
Air inside the system tends to rise. Rising air cools and condenses forming clouds and sometimes precipitation.
What is an air mass
air masses are large bodies of air with uniform temperature, humidity, and pressure.
how are air masses formed
They form when a large high-pressure system lingers over the same area for several days.
how far can air masses extend
They can extend for thousands of miles.
what characteristics change with the land below an air mass
The air in the system takes on the temperature and moisture characteristics of the surface below it.
what are air masses classified by?
Air Masses are classified by their temperature and moisture characteristics.
continental air masses
are formed over land and are dry.
maritime air masses
are formed over water and are moist.
tropical air masses
formed in equatorial regions and are warm
polar air masses
formed in cold regions and are cold.
arctic air masses
formed near the poles and are very cold.
maritime tropical air masses
formed in equatorial regions over water and are warm and moist.
maritime polar air masses
formed in cold regions over water and are cold and moist.
continental tropical air masses
formed in equatorial regions over land and are warm and dry.
continental polar air masses
formed in cold regions and over land and are cold and dry.
what is a weather front
a weather front is a boundary between two air masses
what are common at fronts
Drastic weather: changes in temperature, humidity, cloud type, wind, and precipitation
cold front
forms when a colder air mass moves towards a warmer air mass.
what is common near a cold front
Showers and Thunderstorms are common along the front. Strong winds and severe weather are common.
what happens in a cold front
The cold dense air pushes underneath the warm air causing the warm air to rise.
Water vapor condenses and clouds form.
warm front
forms when less dense warm air moves towards colder, denser air.
what happens in a warm front
The warm air rises as it glides above the cold air. Water vapor condenses creating a wide blanket of clouds.
what is common near a warm front
Showers and steady rain may occur
for several hours or even days.
Brings warmer temperatures and
a shift in wind direction.
stationary front
formed when the boundary between two air masses stalls.
what happens in a stationary front
Usually create clouds and light rain.
occluded fronts
formed when a fast moving cold front
catches up with a slow moving warm front.
what happens in an occluded front
usually bring precipitation
thunderstorm
also known as electrical storms because of their lightning. Are formed when there is warm temperature, moisture, and air rising.
A cumulus cloud can grow into a 10km tall cumulonimbus cloud in as little as __ minutes.
30
cumulus stage
dominated by cloud formation and updrafts.
mature stage
has updrafts, downdrafts, strong winds, heavy rain, and lighting.
dissipating stage
Updrafts usually stop within 30 minutes of reaching the mature stage, winds die down, lightning ceases, and precipitation weakens.
how does lightening form
Tiny ice crystals inside the cloud crash into each other, creating positively and negatively charged particles. When the positive and negative charges find a pathway to the opposite charge, lightning is formed.
how can lightening go
ground-cloud, cloud-ground, and cloud-cloud
how many degrees can a lightening bolt be
27,000˙C
how is thunder formed
At that temperature
air molecules nearby expand and
then contract
tornado
a violent whirling column of air in contact with the ground.
what is the average diameter of a tornado
several 100 meters/ a few football fields
tornado wind speeds can reach more than ___ km/hr/ 250mph
400
how long does a tornado last
a few minutes to several hours
how does a tornado form
when thunderstorm updrafts begin to rotate, swirling winds can begin to spiral downwards creating a funnel cloud. When the funnel cloud reaches the ground a tornado is formed.
tornado alley
The region of the central United States from Nebraska to Texas experience the most tornadoes on Earth.
ideal conditions for a tornado
Cold air blowing southward from Canada
frequently collides with warm, moist air
moving northward from the Gulf of Mexico.
who developed a
method of classifying tornadoes
based on the damage they cause.
Dr. Ted Fujita
hurricane
an intense tropical storm
with winds exceeding 119 km/h.
how long is the typical hurricane
480 km across.
the typical hurricane conditions
late summer over warm, tropical ocean water.
what is at the center of a hurricane
the eye, it has clear skies and light winds
what is the main cause of hurricane damage
high winds and flooding
when do hurricanes lose power
when they move over land or cold water`
other names for hurricane
typhoon or tropical cyclones
blizzard
a violent winter storm
what is a blizzard characterized by
freezing temperatures, strong wind, and blowing snow.
Can reduce visibility, and cause frostbite and hypothermia..
what can blizzards cause
reduced visibility, frostbite, and hypothermia
what issues weather warnings and watches
National Weater Service
severe weather watch
means severe weather is possible
severe wea t /
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