End Show Slide 1 of 26 Copyright Pearson Prentice Hall 4-1 Climate

End Show Slide 2 of 26 THINK ABOUT IT When you think about climate, you might think of dramatic headlines: “Hurricane Sandy Devastates the East Coast!” or “Rain Causes Flooding in the West!” But big storms and seasonal droughts are better described as weather rather than climate. What is climate, and how does it differ from weather? How do climate and weather affect organisms and ecosystems? Copyright Pearson Prentice Hall

End Show Slide 3 of Objectives 1.Differentiate between weather and climate 2.Identify the factors that influence climate Copyright Pearson Prentice Hall

End Show 4-1 The Role of Climate Slide 4 of 26 Copyright Pearson Prentice Hall What Is Climate? Weather is the day-to-day condition of Earth's atmosphere at a particular time and place. Climate refers to the average year-after-year conditions of temperature and precipitation in a particular region.

End Show 4-1 The Role of Climate Slide 5 of 26 Climate is rarely uniform even within a region. Environmental conditions can vary over small distances, creating microclimates. For example, in the Northern Hemisphere, south-facing sides of trees and buildings receive more sunlight, and are often warmer and drier, than north-facing sides. These differences can be very important to many organisms. Copyright Pearson Prentice Hall

End Show Slide 6 of 26 Plants and animals vary in their adaptations to temperature, rainfall, and other environmental conditions. All species have a low tolerance for conditions outside their normal ranges. Alligators, for example, cannot tolerate extreme cold and cannot survive in areas where there is a prolonged winter. The climate of their ecosystems is very important to alligators. Copyright Pearson Prentice Hall

End Show 4-1 The Role of Climate Slide 7 of 26 Copyright Pearson Prentice Hall What Is Climate? Climate is shaped by: 1. Solar energy trapped in the biosphere 2. Latitude 3. Transport of heat by winds and ocean currents

End Show 4-1 The Role of Climate Slide 8 of 26 Copyright Pearson Prentice Hall The Greenhouse Effect The main force that shapes climate is solar energy that arrives as sunlight that strikes the Earth’s surface. Some of the energy is reflected by the atmosphere right back into space but some of it is absorbed by the gases in the atmosphere and is converted into heat. Atmospheric gases that trap the heat energy of sunlight and maintain Earth's temperature range include: carbon dioxide methane water vapor

End Show 4-1 The Role of Climate Slide 9 of 26 Copyright Pearson Prentice Hall The Greenhouse Effect This natural situation in which heat is retained in Earth’s atmosphere by this layer of gases is called the greenhouse effect. Sunlight Earth’s Surface Atmosphere Some heat escapes into space Greenhouse gases trap some heat

End Show 4-1 The Role of Climate Slide 10 of 26 These “greenhouse gases” function like glass in a greenhouse, allowing visible light to enter but trapping heat. The heat that stays in the biosphere determines Earth’s average temperature. Copyright Pearson Prentice Hall

End Show 4-1 The Role of Climate Slide 11 of 26 The greenhouse effect was an important factor in the development of life on Earth. The trapping of heat by greenhouse gases allowed the Earth to warm sufficiently for a variety of life forms to exist. Without the greenhouse effect, the Earth would be at least 30 O C cooler. Copyright Pearson Prentice Hall

End Show 4-1 The Role of Climate Slide 12 of 26 Global Climate Change An increase in the amount of “greenhouse gases” has occurred since the late 19 th century. This increase is primarily due to human activity – increases in manufacturing, transportation, and power generation. As a result, scientists have tracked an increase in the average temperature of the biosphere. They call it global warming. Global warming can have catastrophic effects on many ecosystems – droughts, floods, and intense storms are likely to occur. The polar bear, for example, is threatened with extinction due to the melting of the polar ice caps. Copyright Pearson Prentice Hall

End Show 4-1 The Role of Climate Slide 13 of 26 Copyright Pearson Prentice Hall The Effect of Latitude on Climate At the equator, energy from the sun strikes Earth almost directly. The curvature of Earth causes the same amount of solar energy that strikes the Earth at the equatorial region to be spread out over a much larger area from the equator to the poles.

End Show 4-1 The Role of Climate Slide 14 of 26 Copyright Pearson Prentice Hall The Effect of Latitude on Climate Earth’s polar areas annually receive less intense solar energy, and therefore heat, from the sun. As a result of differences in heat distribution, Earth has three main climate zones: polar, temperate, and tropical

End Show 4-1 The Role of Climate Slide 15 of 26 Copyright Pearson Prentice Hall The Effect of Latitude on Climate The tropical zone, or tropics, is near the equator, between 23.5° North and 23.5° South latitudes. The tropics receive direct or nearly direct sunlight year-round, making the climate almost always warm.

End Show 4-1 The Role of Climate Slide 16 of 26 Copyright Pearson Prentice Hall The Effect of Latitude on Climate The temperate zones sit between the polar zones and the tropics. The polar zones are located in the areas around the North and South poles, between 66.5° and 90° North and South latitudes. Temperate and polar zones receive very different amounts of solar energy at different times of the year because Earth’s axis is tilted.

End Show 4-1 The Role of Climate Slide 17 of 26 As Earth revolves around the sun, solar radiation strikes different regions at angles that vary from summer to winter. During winter in the temperate and polar zones, the sun is much lower in the sky, days are shorter, and solar energy is less intense. Copyright Pearson Prentice Hall

End Show 4-1 The Role of Climate Slide 18 of 26 Copyright Pearson Prentice Hall Heat Transport in the Biosphere The unequal heating of Earth’s surface creates wind and ocean currents, which transport heat and moisture. Earth has winds because warm air is less dense and rises, and cool air is more dense and sinks.

End Show 4-1 The Role of Climate Slide 19 of 26 Warm air over the equator rises, expands, and spreads north and south. It carries heat with it and loses it along the way. As the warm air loses heat and cools, it sinks. When it sinks, it pushes the air below it outward. This air then warms as it travels over the surface of the Earth towards the equator. When warm, it rises again! Copyright Pearson Prentice Hall

End Show 4-1 The Role of Climate Slide 20 of 26 The upward and downward movement of air creates air currents, or winds, that move heat through the atmosphere, from the equator to the north or south. The prevailing winds, then, bring warm or cold air to a region, affecting its climate. Copyright Pearson Prentice Hall

End Show 4-1 The Role of Climate Slide 21 of 26 In addition, Earth’s rotation causes winds to blow generally from west to east over the temperate zones and from east to west over the tropics and the poles. Copyright Pearson Prentice Hall

End Show 4-1 The Role of Climate Slide 22 of 26 Copyright Pearson Prentice Hall Heat Transport in the Biosphere Similar patterns of heating and cooling occur in Earth’s oceans. Cold water near the poles sinks, then flows parallel to the ocean bottom, and rises in warmer regions. This water rising in warmer regions is a process called upwelling. Water is also moved at the surface by winds. In both cases, the movement of the water creates ocean currents, which, like air currents, transport heat energy throughout the biosphere.

End Show 4-1 The Role of Climate Slide 23 of 26 In addition, ocean currents add moisture and heat to air that passes over them. Cool surface currents cool the air that passes over them. In this way, ocean currents can affect the weather and climate of landmasses as air currents do. Copyright Pearson Prentice Hall