Transcript Chapter 3
Chapter 3 Climate and Vegetation Section 1 Seasons and Weather Seasons Earths Tilt- the earth is tilted at a 23.5% angle in relationship to the sun. This means that different parts of world receive direct sun rays more hours of day at different times of the year. This affects our weather and climate. Two latitude lines the tropic of Cancer and the tropic of Capricorn mark the farthest points north and south that the sun shines directly over head at noon. The days that this occurs is called the solstice. Seasons Cont. Summer solstice is the longest day of the year and marks the beginning of summer. Winter solstice is the shortest day of the year and marks the beginning of winter. Another signal for seasonal change are the equinoxes. Equinox occurs twice a year when the days and nights are of equal link all over the world. Seasons Cont. The equinoxes mark the beginning of spring and autumn (fall). Weather Weather-is the condition in the atmosphere at a particular location and time. Climate-is the term for weather conditions in a particular place over a long period of time. Weather What causes weather? Water vapor-this determines whether there will be precipitation. Precipitation-is falling water droplets in the form of rain, sleet, snow, or hail. Cloud cover-clouds hold water vapor Landforms and Bodies of Water-Water heats slowly and looses heat slowly. Land heats quickly and looses heat quickly. Weather Cont. Causes of Weather Cont. Elevation-as elevation increases the air becomes thinner and looses its ability to hold water. Air Movement-wind moves solar energy and air. Moisture is also moved as the air it is in moves. Weather can change very rapidly. Weather Cont. Precipitation Precipitation depends on the amount of water vapor in the air. As warm air rises it cools and loses its ability to hold water vapor. The water vapor condenses and forms into clouds. When the clouds become to heavy precipitation falls. There are three categories of precipitation. Weather Cont. Types of precipitation Convectional-Sun heats warm moist air, clouds form and rain falls. Orographic-occurs in mountain areas. Rain occurs on the windward side of the mountain and little rain occurs on the leeward side of the mountain. The land on the leeward side is called a rain shadow because it gets little rain due to descending dry air. Rain Shadow animation Weather Cont. Types of Precipitation Frontal-this type of precipitation usually occurs in the middle latitudes when cold dense air masses push lighter warm air masses upward causing precipitation to fall. Convectional, Orographic, Frontal Weather Extremes Hurricanes-storms that form over warm tropical waters. They are know as typhoons in Asia. When air flows over ocean waters that are 80 degrees, the winds pick up large amounts of moisture and heat energy. As the winds flow into a low pressure core they tighten and form eyes. Hurricanes can reach wind speeds up to 200 miles per hour. They cause wind damage and flooding. Weather Extremes Tornado-powerful funnel shaped column of spiraling air. Wind can reach speeds of 300 miles per hour. Tornados can occur with out warning and cause catastrophic damage. Blizzard-heavy snow storm with winds of 35 miles per hour or greater. Drought-long period of time without rain. Texas went through a drought in 2000 (84 days without rain). Section 2 Climate Factors Effecting Climate Wind Currents Wind currents help distribute the sun’s heat from one place to another. Convection is transfer of heat in the atmosphere by upward motion of the air. Warm air flows to the poles and cold air flows towards the equator. The actual wind currents bend due to the rotation of the earth. Factors Affecting Climate Ocean Currents Ocean currents are like large rivers flowing through the ocean. Cold currents flow toward the equator and warm currents flow toward the poles. Winds that blow across these currents create climate. For example Europe has a mild climate even though it is a far north as Canada. This is caused by the Gulf Stream and North Atlantic Drift. Factors Affecting Climate Zones of Latitude The world is divided into three latitude zones 1. Low-Tropical Climate 2. Middle-Temperate Climate 3. Higher-Polar Climate Factors Affecting Climate Elevation-The higher the elevation the cooler the climate. Topography-Landforms such as mountains affect climate. Remember from section two the windward side of a mountain gets more precipitation than the leeward side. Changes In Climate Climate changes over time. Some changes are natural and some changes occur as the result of human activity. El Nino- Warming waters off the west coast of South America cause above average rain in the Americas. La Nina-Is the opposite of El Nino and causes dryer patterns in the Americas and wetter patterns in Asia. Section 3 World Climate Regions Defining A Climate Region Climate regions can tell geographers many things about a region without actually giving many local details. Temperature and precipitation are the two most important factors in defining a climate. Topography and elevation also define climates. Latitude zones are also used to determine climate. There is a transitional zone on the borders of climate zones. http://www.classzone.com/books/earth_science/terc/c ontent/visualizations/es2103/es2103page01.cfm?chap ter_no=21 Types Of Climates Tropical Wet- little variation in temperature (80 degrees). Rain fall averages over 80in per year. (Central and South America, Africa, and parts of Asia.) Tropical Wet and Dry- Rainy summers and dry winters. These climate zones border tropical wet climate zones. (Central and South America, Africa, and parts of Asia.) Types Of Climate Semiarid- Receives around 16in. of rain per year. Summers are hot and winters are mild to cold. Usually some of the most productive agricultural lands. Desert- Deserts are classified for the amount of rainfall they receive. Hot deserts like the Sahara are mostly sand. However the deserts in the northern hemisphere that are created by rain shadows can be warm in the summer and freezing in the winter. Types Of Climate Mediterranean- Summers are dry and hot, winters are cool and rainy. The west coast of the U.S. has a Mediterranean climate. Marine West Coast- Cloudy, cool, and damp with consistent temperatures. Washington, Oregon, Canada, Northern California. Humid Subtropical- La Granges Climate. Humid and hot summers with cool winters. Types Of Climates Humid Continental- Great variety in temperature and precipitation. They truly experience all four seasons. Subartic- Huge temperature swings in the seasons. Evergreen forest with short cool summers and long cold winters. Tundra-Flat treeless lands forming a ring around the artic circle. Permafrost-year round frozen sub-soil. Types Of Climate Ice Cap- Snow, Ice, and permanent freezing temperatures. Coldest temperature ever recorded 128 below zero. Highlands- temperature and precipitation vary with latitude, elevation, and other topography. Many times it depends on which side of the mountains you are on. Section 4 Soils and Vegetation Soil Regions Soil is a thin layer of weathered rock, humus, air, and water. The worlds food supply depends on the first six inches of soil called top soil. The quality of top soil determines what vegetation can be grown. Vegetation Regions Natural environments that provide farming, raising of livestock, and timber production. Ecosystem-an interdependent community of plants and animals. Biome-an ecosystem of a region. Vegetation Regions Forest regions are categorized by the types of trees they support. Deciduous-broad leaf trees such as maple, oak, birch, and cottonwood. These trees shed their leaves once a year. Coniferous-Cone bearing needle leaf trees. Vegetation Regions Grasslands Savannas are flat, grassy, mostly treeless plains in tropical grassland regions. Steppe is a term used to name grasslands that are temperate in the northern hemisphere. They are also called praires. Vegetative Regions Desert and Tundra The plants that live in these extreme climates have adapted over time to tolerate the conditions. Human Environment We have a huge impact on the plants and landscape of planet earth. We have made many changes for good and bad.