Atmosphere Basic
What makes up the Atmosphere?
-Combination of gases, dust, water droplets, and ice crystals -Surrounds the Earth -Extends from the Earth’s surface to outer space Gases -Earth’s atmosphere consists mainly of nitrogen (78 percent) and oxygen (21 percent). -The amounts of nitrogen and oxygen in the atmosphere are fairly constant over recent time. -The concentrations of some atmospheric gases are not as constant over time. -The amount of water vapor, ozone, and carbon dioxide vary significantly from place to place. -Invisible, gaseous form of water -Can range of 0% - 4% -Concentration depends on the seasons, altitude, and properties of the surface underneath -During the past 150 years, the concentration of atmospheric carbon dioxide has increased, due primarily to the burning of fossil fuels. -Currently 0.039% (up by 0.028%) -Mostly in ozone layer (20 – 50 km above) -Only 0.0012% but plays important role in blocking out harmful rays from the sun -Concentration has decreased due to CFCs which are now banned -Scientists estimate it should fully recover by the 2100 |
Atmosphere Particles
-Contains variable amounts of solids in the form of tiny particles, such as dust, salt, and ice -Fungi and bacteria are often attached to these particles What are the layers of the Atmosphere? Troposphere -Closest to the Earth’s surface -Contains most of the atmosphere’s mass -Weather occurs in this layer -Air temperature decreases with altitude -Top is called tropopause Stratosphere -Above tropopause -Contains the ozone layer -Air temperature increases with altitude since the ozone layer absorbs the sun’s energy -Ends at the stratopause Mesosphere -Above the stratopause -Air temperature decreases with altitude since very little solar radiation is absorbed -Ends at mesopause Thermosphere -Low air density so temperature rises (can be over 1000°C) -Contains the ionosphere (made up of charged particles) -Ends at thermopause Exosphere -Outermost layer -Transitional region between the Earth’s atmosphere and outer space |
-Remember – all matter is made of particles in constant, random motion!
-These moving particles contain kinetic energy. -The total kinetic energy of the moving particles is called thermal energy -Heat is the transfer of thermal energy from regions of higher temperature to regions of lower temperature How is energy Transferred? -In the atmosphere thermal energy is transferred by: -Radiation -Conduction -Convection Radiation -Transfer of thermal energy by electromagnetic waves -Thermal energy is transferred from the Sun to Earth by radiation -Incoming solar radiation is either reflected back into space or absorbed by Earth’s atmosphere or its surface. -30% reflected -20% absorbed by atmosphere and clouds -50% absorbed by Earth’s surface -Depends on physical characteristics of the surface and the amount of solar radiation -Examples – water heats and cools more slowly; dark colors absorb energy faster Conduction -Transfer of thermal energy when objects at two different temperatures are in contact -Occurs between the Earth’s surface and lowest part of the atmosphere Convection -Remember – convection is the transfer of thermal energy by the movement of heated material from one place to another -Near the Earth’s surface air becomes heated, expands, and rises then as it rises it cools, contracts, and sinks. -This creates convection currents in the atmosphere |
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Moisture in the Atmosphere
What is Dew Point?
-varies depending on water content of the air -when temperature reaches dew pint, condensation can occur How does air pressure an density work in the Atmosphere? -air near the earths surface is denser than air further up -higher you go the lower the pressure because the less materials or particles above you -as temperature raises pressure goes up, this is called a direct relationship -as temperature goes up the density decreases, this is called an inverse relationship How do winds move in the Atmosphere -warm air has a lower density and rises causing lower pressure -cooler air has a higher density and falls causing high pressure How do clouds form? -warm moist air rises -air expands an cools -air reaches its dew point -water droplets condense around condensation nuclei -Orographic Lifting -warm air encounters cold air What are the types of clouds? -Cirro- high clouds with bases startting above 6000 -Alto-midlle clouds 2000-6000 -Strato-low clouds 2000 -Cirrus- latin meaning hair -Cumulus- lumpy looking -Stratus-layered clouds -Nimbus- low gray rain clouds |
Air Masses and Front
What are Air Masses?
-An air mass is a large volume of air that has the same characteristics, such as humidity and temperature, as its source region. -A source region is the area over which an air mass forms. What are the types of Air Masses? 1. The origins of maritime tropical air are tropical bodies of water. 2. The southwestern United States and Mexico are the source regions of continental tropical air, which is hot and dry, especially in summer. 3. Maritime polar air masses form over the cold waters of the North Atlantic and North Pacific. 4. Continental polar air masses form over the interior of Canada and Alaska, and carry frigid air southward in the winter. 5. Earth’s ice- and snow-covered surfaces above 60° N latitude in Siberia and the Arctic Basin are the source regions of arctic air masses. What are our two pressure systems?
-Sinking or rising air, combined with the Coriolis effect, results in the formation of rotating high- and low-pressure systems in the atmosphere. 1.Low-pressure System -In surface low-pressure systems, air rises. When air from outside the system replaces the rising air, this air spirals inward toward the center and then upward. -Clouds and precipitation 2. High-pressure Systems -In a surface high-pressure system, sinking air moves away from the system’s center when it reaches Earth’s surface. -Clear skies and fair weather. |
What things impact weather?
-The directions of Earth’s winds are influenced by Earth’s rotation. -This Coriolis effect results in fluids and objects moving in an apparent curved path rather than a straight line. What are the 3 wind systems? 1. Polar Easterlies -The polar easterlies are the wind zones between 60 N latitude and the north pole, and 60 S latitude and the south pole. 2. Prevailing Westerlies -The prevailing westerlies are the wind systems on Earth located between latitudes 3 N and 60 N, and 30 S and 60 S. 3. Trade Winds -Between latitudes 30 N and the equator is a circulation belt of wind known as the trade winds What are our four types of fronts? -A collision of two air masses forms a front—a narrow region between two air masses of different densities 1. Cold Front -When cold, dense air displaces warm air, it forces the warm air, which is less dense, up along a steep slope. This type of collision is called a cold front. -Intense precipitation and sometimes thunderstorms. 2. Warm Front -Advancing warm air displaces cold air along a warm front. A warm front develops a gradual boundary slope. -Widespread light precipitation 3. Stationary Front -When two air masses meet but neither advances, the boundary between them stalls. This stationary front frequently occurs between two modified air masses that have small temperature and pressure gradients between them. -Sometimes light winds and precipitation 4. Occuleded Front -Sometimes, a cold air mass moves so rapidly that it overtakes a warm front and forces the warm air upward. As the warm air is lifted, the advancing cold air mass collides with the cold air mass in front of the warm front. A warm air mass is squeezed upward between two cold air masses -Strong winds and heavy precipitation |
Prediction Weather
-Two important factors in weather forecasting are the accuracy of the data and the amount of available data.
What are the tools we use to measure weather? -A thermometer measures temperature using either the Fahrenheit or Celsius scale. -A barometer measures air pressure -An anemometer measures wind speed. -A hygrometer measures relative humidity -The instrument used for gathering upper-atmosphere data is a radiosonde. -A radiosonde’s sensors measure the air’s temperature, pressure, and humidity. -Also wind speed and direction( by its movement) -Analysis of Doppler radar data can be used to determine the speed at which precipitation moves toward or away from a radar station. Satellites -Infra red, 2. visible light, 3.water vapor imagery. -Some satellites use cameras that require visible light to photograph Earth. -These digital photos are sent back to ground stations, and their data are plotted on maps. Unlike weather radar, which tracks precipitation but not clouds, satellites track clouds but not necessarily precipitation. |
How do we display the information that we gather?
-A station model is a record of weather data for a particular site at a particular time. -Meteorological symbols are used to represent weather data in a station model. Advantages: universal language, more info in less space. -To plot data nationwide and globally, meteorologists use lines that connect points of equal or constant values. -Lines of equal pressure are called isobars. -Lines of equal temperature are called isotherms. How do we forecast the weather? -A digital forecast is created by applying physical principles and mathematics to atmospheric variables and then making a prediction about how these variables will change over time. -An analog forecast is based on a comparison of current weather patterns to similar weather patterns from the past. |