Transcript Weather Unit 2

WEATHER UNIT 2
Meteorology and the Nature of Storms
WEATHER VS. CLIMATE
• Weather – short term variations in
atmospheric conditions
• Climate -is the long term average of
variations in weather for a particular
area, usually over 30 years of more.
What causes weather?
• The main cause of all weather is the
imbalanced heating of the Earth’s
surface.
• As the various areas of Earth are
heated differently, the air interacts in
various ways which we will study in
this section.
HEATING THE EARTH'S SURFACE
The majority of the Sun’s rays are reflected back to space.
However, the increase if Greenhouse Gases from burning of fossil fuels is causing more rays to
be blacked back to the earth’s surface, therefore, causing the global average temperature to
increase.
CONNECTING AIR MASSES TO
FRONTS
• Front is the front of an air mass, carrying
the characteristics of the air mass.
• When air masses mix, warm rises and cold
sinks creating rainy and sometimes violent
weather.
Fronts- The boundary at the front of an air mass
The front created depends on the characteristics of the air
mass..
A. Cold Front – Cold air moves in, forcing warm air
up. Intense precipitation and storms are common
with cold fronts.
B. Warm Front – Warm air moves in, displacing the
cold air. The warm air rises gradually causing
widespread light precipitation.
C. Stationary Front – When 2 air masses meet but
neither advances. They are usually similar in
temperature. Causes cloudy weather with light
winds and occasional precipitation.
D. Occluded Front – When a cold front catches up to
and takes over a warm front. Warm air is forced up
violently. Typically causes strong winds and heavy
precipitation.
http://www.physicalgeography.net/fundamentals/7r.html
THE JETSTREAM
• Jetstream is a fast-moving upper level wind that
was created from a combination upper-level air
and the Coriolis effect.
• It is a narrow band of fast wind that separates
cold air from the north and warm air from the
south.
• It is generally located in the region with the
strongest temperature difference, so its location
varies season to season as well as slit but is the
sole power of our weather.
The Jetstream and Global
Climate Change
•
Yale and Rutgers story on
Jetstream
• http://climatestate.com/2014/
01/05/polar-vortex-jet-streamand-climate-change/
•
NPR.org on the Jetstream
• http://www.npr.org/2013/09/2
5/225754902/wild-weathertied-to-unusual-jet-streamactivity
THE JETSTREAM CONTINUED:
PRESSURE SYSTEMS
High Pressure System
• More dense systems, can “Push” other
systems out of its way
• Usually brings cooler temperatures with
no precipitation
• Weather is very pleasant
Low Pressure System
• Warm air rises and spirals inward.
• Then begins to rotate counter clock wise.
• Risen air condenses to clouds and
precipitation.
• Global winds carry the system across US
WEATHER FORECASTING
Ice Storm Atlanta,
Georgia
Snow Canyon Toyama,
Japan
ISOTHERMS AND ISOBARS
Isotherms – Lines on a weather
map of equal temperature.
Isobars – Lines on a weather map of
equal pressure.
What are some other devices that are used to help predict the weather?
Station Model
A station model is a record of weather data for a particular area
at a particular point in time.
The station model’s data is put-together to determine the
weather patterns not only for that present time but also for the
weather of the next several days.
SUPERCELLS AND DOWNBURSTS
A supercell in Montana
.
Supercells are intense rotating
storms in which updrafts can
take 10-20 minutes to reach
the top of the clouds.
Downbursts are violent downward
drafts of wind with speeds over
100 mph. These winds can cause
as much damage as tornadoes.
Thunderstorms:
Tornadoes: TORNADO FORMATION
Formation of a Thunderstorm:
•
Tornados:
Pop-up Thunderstorms- form in spring in summer
during the afternoon from unequal heating of the
surface.
•
Wind speeds uneven between high in the
atmosphere and ground
•
Causing horizontal columns of circulating air
Frontal Thunderstorms when a cold air mass
•
pushes under a warm air creating uplift and
energy. These storms are massive and can create
hail and tornadoes.
Thunderstorm’s updrafts will then turn these
columns vertical. Once below the clouds – a
tornado has formed
Thunder: the sound of the air rapidly expanding
and contracting the cloud, but sound travels
slower than light.
Lightning: As a cloud charges with static electricity
from friction within the updrafts,
TORNADO ALLEY
HURRICANES
Inside view of Hurricane
from Planes that drop
probe for readings
HURRICANE FORMATION
Hurricane- A well-defined circulation with
winds at least 118km/hr.
Interactive hurricane
How they form
Storm surge
• A wall of water created as hurricane-force winds force ocean water toward
land.
Mantoloking, NJ
GREENHOUSE EFFECT AND GLOBAL WARMING
Greenhouse Effect-the natural heating of
Earth’s surface by certain atmospheric
gases, which helps keep Earth warm
enough to sustain life.
Global Warming-rise in global
temperatures, which might be due to
increases in atmospheric CO2 from
deforestation and burning of fossil fuels.
Inconvenient Truth version
of Global Warming
If Half of Antarctica melted
GLOBAL CLIMATE CHANGE
So, the Earth's average temperature has
increased about 1 degree Fahrenheit during
the 20th century. What's the big deal??
At the end of the last ice age, when the
Northeast United States was covered by
more than 3,000 feet of ice, average
temperatures were only 5 to 9 degrees
cooler than today.
NATURAL DISASTERS
•
2011 Natural disasters
PART II- BIOMES
BIOME PICTURE AND NOTES WALK
1. Walk around and examine EACH slide on a
different biome.
2. Observe the pictures closely to understand the
type of life that exists there as well as example
locations.
3. After reading each slide, complete the worksheet
for the required content on each biome.
GRASSLANDS AND SAVANNA
 Dry climate 100-20cm
 Also, grasslands tend to be in
temperate to subtropical areas, often
with cold winters and hot summers.
 Found between deserts and forests
 In the northern hemisphere the main
grasslands are the prairies of the midwestern United States and Canada; in
Eurasia the maker grasslands are the
steppes of Russia and the grasslands
of the mid-east extending from Turkey to
India. Grasslands are also found in
South America.
 Threats: There are two major threats to
grasslands - conversion to agriculture
(or urban areas) and global warming
and its attendant changes in
precipitation. Also, mining, animal
poaching and development
DESERT
• precipitation is low, less than 100 cm
per year
• average annual temperature is less
than 10° C.
• subtropical deserts- latitudes of 30°
North or South latitude (equator)
• Temperate deserts- "grassland" from
"desert".
• Locations from southern California,
North/central Africa, Central Asia and
central Australia
Subtropical deserts
• Threats-one of the biggest threats to
deserts is development.
Temperate deserts
TAIGA OR BOREAL FOREST
• Climate in the taiga is cold, with
average annual temperatures from
about +5° to -5° C
• 20 cm of precipitation per year to over
200 cm
• growing season is short, usually less
than 3 months.
• broad bands across North America
and Eurasia (Russia/Siberia)
• Coniferous trees
• Threats-animal poaching, exploration
and development of oil and natural
gas reserves, development and
logging is always a threat however,
most serious threat is Global
Warming.
TEMPERATE DECIDUOUS FOREST
• Rapid changes from cold and dry to wet
and warm or to any of the other corners
of the climate envelope are often swift
and dramatic.
• The average annual temperature ranges
up to about 20° C down to freezing.
• Precipitation ranges from around 50 cm
yr in the colder regions to over 200
cm/yr. (lake-effect snows in the winteruntil the lake freezes).
• Broad-leaf vegetation
• Threats- Acid Rain, logging, human
population and development, global
warming also the soils are rich and
easily converted to agriculture
RAINFOREST
 Warm and wet -250cm of rain per year to
about 450 cm/year. The average annual
temperature is above 20° C (never a
frost)
 tropics, a band around the equator from
23.5° N (the Tropic of Cancer) to 23.5° S
(the Tropic of Capricorn)
 solar radiation is most intense
 The warmth leads to a lot of evaporation,
and as warm, moist air rises, it cools, the
water condenses, and the water falls
back to the earth as rain. Thus, the
warmest areas of the planet also tend to
be the wettest, and this sets the stage for
the tropical rain forest. Another biome
similar to the tropical rain forest is the
cloud forest.
 Threats-animal poaching, sustenance
farming, human population growth,
Industrialized agriculture, logging and
other minerals and resources being
removed for human use.
TUNDRA
• In the tundra, conditions are cold, with
an annual average temperature less
than 5° C, and precipitation (mostly in
the form of snow) less than 100 mm per
year (see figure at right).
•
The summer is brief, with temperatures
above freezing lasting for only a few
weeks at most.
• The ecology of the tundra is controlled by
the cold climate and the northern
latitude. The former means that a
unique soil structure, permafrost, forms
and dominates the biology.
• Lichens and mosses, willows, sedges
and grasses
• Threats-airborne pollutants, oil and
gas development , global warming