Page 1 of 5 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. Page 2 of 5 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’. Page 3 of 5 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. Page 4 of 5 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. Page 5 of 5 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.