ES Chapter 13 Atmosphere and Climate
Terms in this set (33)
State of the atmosphere at a particular place at a particular time.
The long-term prevailing weather conditions at a particular place based upon records taken. Determined by latitude. atmospheric circulation patterns, oceanic circulation patterns, geography, solar activity, and volcanic activity. The most important factor is the distance from the equator.
Distance from the equator measured in degrees north or south. The equator is located at 0 degrees latitude. The North Pole is the farthest north from the equator, as it is at 90 degrees north latitude. The South Pole is the farthest south of the equator, at 90 degrees south. Latitudes influence climate because the amount of solar energy an area of earth receives depends on its latitude. More solar energy falls on areas that are near the equator than on areas that are closer to the poles. In regions near the equator, night and day are both about 12 hours long throughout the year. Temperatures are also high year round and there are no summers or winters.
In regions closer to the poles, the amount of energy arriving at the surface is reduces. In the northern and southern latitudes, sunlight hits the earth at oblique angle and spreads over a larger surface area than it does at the equator. Yearly average temperatures are lower than they would be at the equator. The hours of daylight vary. Near the poles, the sun sets for only a few hours each day in summer and rise for only a few hours each day in the winter.
Cold air sinks because it is denser than warm air. As cold air sinks, it compresses and warms. Warm air rises. It expands and cools as it rises. Warm air can hold more water vapor than cold air can. Therefore, when warm air cools, the water vapor it contains may condense into liquid water to form rain, snow, and fog. Solar energy heats the ground, which warms the air above it. Because the earth rotates, and because different latitudes receive different amount of solar energy. This determines earth's precipitation pattern. The intense solar energy striking earth's surface at the equator causes the surface as well as the air above the equator to become very warm. The warm air can hold large amounts of water that evaporate from the equatorial oceans and land. As the warm air rises it cools, which reduces some of its ability to hold water. Areas near the equator receive large amounts of rain. Cool water over the equator cannot sink because hot air is rising below the cool air. The cool air rises and is forces away from the equator toward the north and south poles. Some of this cool air sinks back down to the earth's surface. The air becomes warmer as it descends. The warm dry air moves across the surface of the earth and causes water to evaporate from the land below, which creates dry conditions. Air moving toward the poles warms while it is near the earth's surface. When this rising air reaching the top of the troposphere, a small amount of the air returns back to the circulation patters. Most of this uplifted air is forces toward the poles. Cold, dry air descends at the poles, which are essentially very cold deserts.
When warm air rises and cooler air moves in to replace it.
Winds that blow predominantly in one direction throughout the year. Because of the rotation of the earth, these winds do not blow directly northward or southward. Instead these winds are deflected to the right in the northern hemisphere. They are deflected to the left in the southern hemisphere.
Belts of prevailing winds that blow most of the time in both hemispheres between 30 degrees north and south latitudes and the equator. They blow from the northeast in the northern hemisphere and from the southeast in the southern hemisphere.
Produced between 30 degrees and 60 degrees north latitudes and 30 - 60 degrees south latitudes. IN the northern hemisphere the westerlies are southwest winds. In the southern hemisphere, they are northwest winds. The polar easterlies blow from the pole to 60 degrees north and south of the latitudes.
Oceanic circulation patterns
Water hold large amounts of heat. The movement of surface ocean currents is caused mostly by winds and the rotation of earth. These surface currents redistribute warm and cool masses of water around the planet. Some surface currents warm or cool coastal areas year-round. Affect the climate in many part of the world. Here, we will only discuss surface currents that change their pattern of circulation over time.
The name given to the short term (6-18 months) period change in the location of warm and cold water masses in the Pacific Ocean. Winds in the western Pacific Ocean strengthen and push warm water eastward. Rainfall follows this warm water eastward and produces increased rainfall in the southern half of the U.S. and in equatorial South America. Causes droughts in Indonesia and Australia. The warm phase of the cycle.
The water in the eastern Pacific Ocean is cooler than usual. The cold phase of the cycle.
Pacific Decadal Oscillation
A long term (20-30 years) change in the location of warm and cold water masses in the Pacific Ocean. PDO influences the climate in the northern Pacific Ocean and North America. It affects ocean surface temperatures, air temperatures, and precipitation patterns.
Mountain ranges influence the distribution of precipitation. EX: Sierra Nevada mountains in California. Warm air from the Pacific Ocean blows eats, hits the mountains, and rises. As the air rises, it cools, which causes it to rain on the western side of the mountains. Bu the time the air reached the eastern side of the mountains, it is dry. This is known as a rain shadow.
5,896 m extinct volcano in Tanzania. 3 degrees south of the equator but snow covers its peak year round. Illustrates the important effects of height above sea level (elevation) on climate. Temperatures fall about 6 degrees Celsius for every 1,000 m increase in elevation.
The sun emits an increased amount of ultraviolet radiation. UV radiation produces more ozone, warming the stratosphere. The increased radiation can also warm the lower atmosphere and surface of the earth a little.
In large-scale volcanic eruptions, sulfur dioxide can reach the upper atmosphere. The sulfur dioxide gas reacts with smaller amounts of water vapor and dust in the stratosphere. This reaction forms a bright layer of haze that reflects enough sunlight to cause the global temperature to decrease.
Seasons are due to the tilt of earth's axis (about 23.5 degrees). Because of this tilt, the angle at which the sun's rays strike the art changes as the earth moves around the sun. During the summer in the northern hemisphere, the northern hemisphere tilts toward the sun and receives direct sunlight. The number of hours of daylight is greatest in the summer. Therefore, the amount of time available for the sun to heat the earth becomes greater. During the summer in the northern hemisphere, the southern hemisphere tilts away from the sun and receives less direct sunlight. During summer in the southern hemisphere, the situation is reversed. The southern hemisphere is tilted toward the sun, whereas the northern hemisphere is tilted away.
An area in the stratosphere where ozone is highly concentrated. Absorbs most of the ultraviolet light from the sun. Ultraviolet light is harmful to organisms because it can damage the genetic material in living cells. By shielding the earth's surface from most of the sun's ultraviolet light, the ozone layer acts like a sunscreen for the earth's inhabitants.
Molecule made of three oxygen atoms.
Human-made chemicals. Were thought to be miracle chemicals. They are nonpoisonous and nonflammable and they do not corrode metals. They quickly became popular as coolants in refrigerators and air conditioners. They were also used as a gassy "fizz" for making plastic foams and as a propellant in spray cans of everyday products such as deodorants, insecticides, and paint. Chemically stable, do not combine with other chemicals or break down other substances. Can break apart high in the stratosphere where UV radiation is absorbed. Once they break apart, parts of them destroy the ozone. Each CFC contains 1-4 chlorine atoms. 1 chlorine atom can destroy 100,000 ozone molecules. Ozone produced by pollution breaks down or combines with other substances to replace the ozone that is being destroyed.
A thinning of stratospheric ozone that occurs over the poles during the spring.
During the dark polar winter when strong circulating winds over Antarctica isolate cold air from surrounding warmer air. The air within the vortex grows extremely cold.
Polar stratospheric cloud
When temperatures fall below -80 degrees Celsius, high altitude clouds made of water and nitric acid begin to form. The products of CFCs are converted to molecular chlorine on these clouds. When sunlight returns to the south pole in the spring, molecular chlorine is split into two chlorine atoms by ultraviolet radiation. The chlorine atoms rapidly destroy ozone. This causes a thin spot, or ozone hole, which lasts for several months.
Damages DNA. Can cause skin cancer, premature aging of skin, increased incidence of cataracts, weakened immune system. Can kill many eggs of some species by damaging unprotected DNA. Can damage plants by interfering with photosynthesis and would result in lower crop yields.
Single-celled organisms that live near the surface of the ocean. Loss of these organisms can disrupt the ocean food chains and reduce fish harvests. Could cause an increase in the amount of carbon dioxide in the atmosphere.
Sunlight streams through the atmosphere and heats the earth. As this heat radiated up from the earths surface, some of it escapes into space. The rest of the heat is absorbed by gases in the troposphere and warms the air.
Gases that absorb and radiate heat. water vapor, carbon dioxide, chlorofluorocarbons, methane, and nitrous oxide. Water vapor and carbon dioxide account for the most of the absorption of heat that occurs in the atmosphere.
Installed an instrument at the top of a tall tower on the volcano Mauna Loa in Hawaii. Keeling wanted to measure the amount of CO2 in the air.
Most of the CO2 that is released into the air dissolves in the ocean or is used by plants for photosynthesis. As a result, the levels of CO2 in the air vary with the seasons. During the summer growing plants use more CO2 for photosynthesis. This causes Co2 levels in the air to decrease. In the winter, dying grasses and fallen leaves decay and release the carbon that was stored in them during the summer causing CO2 levels to rise.
The increase of the average temperature at earth's surface.
Consequences of global warming
- Ice melting
- Rising sea levels
- Eroded beaches
- Freshwater aquifers becoming too salty
- Hurricanes and typhoons more common
- Change in ocean current patterns
- Rising temperatures
- Dengue fever
- Demand for irrigation
- Trees could colonize cooler areas
- Cause a shift in geographical range if some animals
Developed countries to decrease emissions of carbon dioxide and other greenhouse gases by an average of 5%.