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Unit II- The Terrestrial Environment. (Pg. 19 Syllabus)


Specific Objective #8
Describe the various types of Air masses:

An air mass is a large body of air that generally has the same moisture
content and temperature throughout.
Air masses spread air pollutants over long distances e.g. Sahara dust,
fumes from industrial sites, fumes from landfills, volcanic dust etc.

Specific Objective#9- pg. 311
Distinguish among the four types of local fronts.

When air masses meet a front is formed.

                      TABLE DEFINING FONTS

Cold       A cold front is defined as the zone where a cold air mass
           replaces a warmer air mass. Most common in the Caribbean.
Warm       A warm front is defined as the zone where a warm air mass
           replaces a cold air mass.
Stationary A Stationary front occurs when the cold front warms up so
           there is no longer a temperature difference between the cold
           front and the warm front.
Occluded An occluded front is formed when a cold front overtakes a
           warm front. When this occurs, the warm air is lifted off the
           ground. Not common in the Caribbean.
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TABLE SHOWING THE WEATHER ASSOCIATED WITH COLD
AND WARM FRONTS.

Cold                                  A cold front is preceded by:
                                      Rapid fall in air pressure
                                      Deep dense clouds (cumulonimbus)
                                      Rain
                                      As the front passes:
                                      Heavy thunderstorms
                                      Intense rain
                                      A drop in temperature
Warm                                  A warm front is preceded by:
                                      A slow fall in air pressure
                                      As the fret passes:
                                      Showers f rain
                                      An increase in temperature

Specific Objective # 10 (pg.312)
Describe the characteristics of a cyclonic strum, particularly a
hurricane.

A cyclone is a region of low atmospheric pressure surrounded by rotating
winds. Hurricanes are extreme cyclones in which the wind speed exceeds
120km/h.

A hurricane forms when moist air, heated by the sun, rises from the
water. As the air rises, it cools and condenses into rain. This releases
energy which powers the hurricane. As the air rises, more hot moist air
rushes in from all sides to replace it. These winds are deflected to the
right so that they come to spiral around a central calm ‘eye’.
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A hurricane watch indicates your area may be in danger. A hurricane
warning means there likely to be direct damage.


Specifc objective # 11
Describe tidal waves and how they are formed.

Cyclonic storms passing over the ocean cause the water to build up into a
huge wave called a STORM SURGE OR TIDAL WAVE. Earthquakes
under water can cause high tidal waves called TSUNAMIS. During an
underwater earthquake the sea floor rises and falls rapidly causing a
Tsunami to develop (pg 315).

Specific Objective # 12 (pg 316-317)
Explain the causes of different types of volcanic eruptions.

Volcanoes are found where plates are moving. At these plates magma
(hot molten rock) is squeezed from the earth’s interior to the surface.
When it reaches the Earth’s surface it is called lava.

Different kinds of volcanoes:

Violent: explode violently e.g. La oufri re
Shield: involve quiet flow of lava
Composite: give a combination of explosive and non explosive eruptions.


The ecological consequences of volcanoes in the short and long term.
(see pg 316)


Specific objective # 13 (pg. 314)
Discuss the relationship between earthquakes and volcanoes.

When earthquakes occur the moving plates heat up and rocks melt. The
molten rock makes its way to the surface of the land and erupts as a
volcano.
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Specific Objective #14 (pg 306-307)

Describe how tides are formed:
     Tides are formed as a result of the force of attraction the moon has
     on the earth (pg.305).

      High tides: are formed when the sun and moon are in line, they
      exert the greatest force on the earth’s water producing high tides
      Low tide: are formed when the sun, earth and moon are at right
      angles to each other, the pull on the earth is weak and low tides are
      produced.
      There are 2 high tides and low tides every day.




Some of the effects of tides: (pg. 306-7)

       TABLE OF HOW ORGANISMS ARE AFFECTD BY THE SEA.
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Rivers              Salinity: High salinity-High    Organisms have to adapt to
                  Tide                              wide range of salinity e.g.
                            Low salinity - Low      crabs, oysters.
                  tide
                  Water currents; Live sheltered
                  in pools in river bank,
                  attached to rocks or are strong
                  swimmers.
Mangrove          Mud level always shifting,        Prop rots- Red mangrove
Swamps            low oxygen content of soil.       Breathing roots- White
                                                    mangrove
Seashore
     Splash       Sea Spray. Exposed to drying Shelled organisms which close
     Zone         and heat of the sun for most of up their shells to prevent drying
                  the day.                        out e.g. small sea snails and
                                                  lichens
     Intertidal
     Zone         Between high tide and low
                  tide.
                                                    Sea snails and limpets which
                  Top: Most of the day affected     can pull down tightly onto the
                  by heating and drying effects     rock so they do not dry out.
                  of the sun.
                                                    Seaweeds, crabs, sea urchins.

                  Bottom: Covered by water
                  most of the day.
     Sub-         Always covered by water.          Seaweeds, soft –skinned
     Littoral                                       animals, sea anemones,
     Zone                                           sponges.
     Rock         Hollowed out areas in the         Same animals as the sub littoral
     Pools        rocks filled with sea water.      Zone
                  Water tends to get hot and
                  salty.

				
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