Climate and Vegetation Chapter 3 Climate and Vegetation

Seasons and Weather Seasons and weather occur because of the changing position of the earth. Weather extremes are related to location on the earth.

Seasons The earths tilt affects seasonal changes Equinox Sun S The earths tilt affects seasonal changes The earth is tilted on its axis at 23.5° in relation to the sun. Solstice Day on which the Earth is at it fullest tilt towards and away from the sun. Longest day (start of summer) and shortest day (start of winter) of the year. Tropic of Cancer and Tropic of Capricorn will receive direct sunlight Equinox The equator receives direct sunlight creating equal day and night around the planet Spring Equinox and Fall Equinox

Weather Weather is the particular condition of the atmosphere at a specific time in a specific area. Weather is affected by: Humidity - amount of water vapor in the air Landforms and Bodies of water - Oceans, lakes, swamps, etc… Water heats and cools slowly, land heats quickly but also loses heat slowly Elevation - the higher in the atmosphere, the less moisture the air can hold Air movement - winds and solar energy creating fronts, jet stream, pressure systems.

Weather (pg 50) Precipitation water that falls from the atmosphere as either rain, sleet snow or hail. Convectional- result from moist air being heated by the daily sun causing air to rise, as the sun descends the air cools off and rains. Orographic- as a mass of air moves over land, the rise in land elevation causes the air to move up. When moisture rises into thinner air the air can no longer hold the moisture and precipitation falls. The region immediately beyond the higher elevation becomes extremely dry, as the air is basically a squeezed out sponge, creates an arid environment called a rain shadow. Frontal- when a warm air mass (front) meets a cooler air mass, the warmer air will be pushed over the cooler and result in rain.

Weather Extremes Hurricanes Tornadoes weather system that forms over warm water that consists of high winds (excess of 74mph), high storm surge (can be more than 25 ft), and flooding rains. Also known as Typhoons in Asia and cyclones in in Australia can take days to develop Tornadoes A tightly spun, spiraling column of air around a low pressure center. Winds can reach an excess of 300 mph and can be up to a mile or more wide. Can form instantly with no warning Can reach speeds of 300+ mph Among the most destructive forces on the planet.

Blizzards Droughts Floods Heavy snowstorm with winds in excess of 35mph and greatly increased snowfall and reduced visibility. Creates road hazards, building structures to collapse, power failures, endangers livestock. Droughts An extended period of time with little to no rainfall. Large areas often experience dust storms which can cause widespread damage to transportation and all machinery caught in these “storms paths Results in crop failures among other problems. Floods Can be caused by sudden downpours and snowmelt in an area not ready to receive the sudden amount Sudden heavy rainfall in areas with a saturated ground or are in a low-lying area with streams or rivers.

Climate Climate is the weather conditions of a place over an extended period of time. Temperature and Amount of Precipitation are used to determine climate Global climatic changes may be caused naturally or can be man-made

Factors affecting climate… Wind currents Warmer air moves towards the poles while cooler air moves towards equator distributing the sun’s heat (convection) Since the earth is rotating the air does not go up and sink at the same location, instead it moves at an angle. globally air moves from the heated equatorial regions toward the polar regions. This bending of the wind is created by the Coriolis Effect Global wind currents are listed on Pg 54 North- and Southeasterly Trade winds, Westerlies, and the Polar Easterlies Ocean Currents Warm water rising, cooler water sinking. Warm flows away from Equator toward poles, cool water flows toward Equator from poles. Winds blowing over ocean currents

Factors of climate Ocean Currents Zones of Latitude Behave similar to wind currents through convection Create “rivers” within the oceans that make a circular pattern of warm water carried to the poles and cooler water toward the equator Affects temperature and precipitation Zones of Latitude Equator receives the most direct sunlight, therefore it is hotter. Therefore, as you move outward toward the poles the air becomes cooler. Divided into three levels defined by the Tropic of Capricorn (southern hemisphere) and the Tropic of Cancer (northern hemisphere) Low or tropical latitudes Middle or temperate latitudes High or polar latitudes

Factors of climate Elevation Topography Air becomes thinner as it rises higher in elevation, because of this the air mass can no longer hold as much moisture Temperatures in higher elevations are less affected by latitude. Mt. Kilimijaro (Tanzania, Africa) is on the equator , but has a permanent ice cap Topography Landforms, such as mountain and highlands, can trap moisture as well as block moisture from reaching into other areas As air moves over land that is gaining in elevation, the mass will be squeezed and moisture will be released. Moisture will only climb in altitude as much as the air holding it can carry, once it reaches a certain altitude it can no longer be transported, thus precipitation occurs. When the air mass is not able to carry the moisture over higher elevated landforms the air mass will move over but the moisture will not causing a Rain Shadow on the other side. Rain shadows are regions on the leeward side of mountains that receive little to no precipitation, usually a dry environment.

Changes in Climate El Nino and La Nina El Nino occurs when the waters off the north eastern coast of South America begin to warm up causing the wind patterns to temporarily reverse from blowing towards Asia and Australia to blow towards the Americas This occurs every 2 to 7 years As winds blow over this warmer water climates shift worldwide La Nina occurs when the same waters become cooler causing the air to reverse El Nino wind patterns back to east to west towards the western Pacific Rim continents.

Changes in Climate Global warming The earth has cycles of heating and cooling When heating occurs glacial ice will melt causing water levels to rise globally resulting in warmer climates. The Greenhouse Effect states that certain gases that are trapped in our atmosphere do not escape the earth’s atmosphere, causing the global temperature to climb. Controversy surrounds this issue as a result of an environmental movement against certain types of industrial growth that use many nonrenewable resources for energy. The argument is industries that burn coal, petroleum and other resources, create harmful gases that retain heat as well as block heat from escaping the earth’s atmosphere Scientist are on both sides of the issue

World Climate Regions See page 60-62 Temperature and amount of precipitaion create climates Location on a continent, topography and altitude affect climate as well. Types of Climate Regions Tropical Wet Tropical Wet and Dry Semiarid Desert Mediterranean Marine West Coast Humid Subtropical Humid Continental Subarctic Tundra Ice Cap Highlands See page 60-62

Soils and Vegetation Soil regions The majority of all life on the planet depends on the top 6 inches of soil. Some areas have deeper topsoil than others Topsoil depth affects the ability of plants to take root. Soil composition (Chapter 2) is different in all parts of the globe Depth and type of soil affect the type of vegetation grown in a region

Soils and Vegetation Vegetation Regions Ecosystems Biomes An interdependent community of plants and animals. Biomes An ecosystem in a specific region. Divided into forestland, grassland, desert, and tundra.

Vegetation Regions Forestlands Categorized two types of trees Broadleaf Also called Deciduous Birch and cottonwood Needleleaf Also called Coniferous (cone-bearing) Pine, Fir and Cedar Tropical Rainforest, Temperate Rainforests, Deciduous and Pine forests, and Mixed Forests.

Vegetation Regions Grasslands Tropical grasslands Temperate Grasslands Known as Savanna Located along the tropic or low latitudes Sparsely dotted with trees Think of “The Lion King” Temperate Grasslands Known as prairies, steppes, or pampas. Located in the temperate or middle latitudes Dotted with trees more than savanna Think of the Great Plains

Vegetation Regions Desert Located anywhere there is a rain shadow Average rainfall is less than 1.5 feet of rain a year Vegetation is dependent on very little rainfall and has ability to store water for extended periods of time. An extremely fragile biome everything thing that lives in this environment is dependent on everything else in this environment. Can be located anywhere on the planet some are cold and some are hot.

Vegetation Regions Tundra Mostly located above the Arctic Circle and below the Antarctic circle, but can be found in higher elevations Ground is frozen limiting and often preventing seed germination and plant growth leaving only small shrubs and plants, otherwise treeless. Permafrost is permanently frozen ground.