Chapter 1 The Earth and Its Atmosphere
There is no upper limit of the atmosphere, but it rather becomes thinner and thinner, merging with empty space. -laughing gas greenhouse effect= warming that results when solar radiation is trapped by the atmosphere; caused by atmospheric gases that allow sunshine to pass through but absorb heat that is radiated back from the warmed surface of the earth. Water is the only substance that can be found naturally in the atmosphere in its 3 phases (solid->ice, liquid->water,gas->water vapor)
Carbon Dioxide cycle Fig. 1-4, p. 7
Vertical Structure of the Atmosphere • Air Pressure and Air Density • Weight(force acting on an object due to gravity) = mass x gravitational acceleration = m x g • Density = mass/volume (air density at sea level ~ 1.2 kg/m3 ) • Pressure = force/area • At the Earth’s surface the pressure of the atmosphere is 14.7 lbs/in2 . • Standard sea level pressure is: 1013.25mb=1013.25hPa=29.92 in.Hg. • Atmospheric pressure decreases with an increase in height.
Vertical Structure of the Atmosphere • Layers of the Atmosphere • Pressure & Density decrease with height • Air temperature has a complicated vertical profile • Lapse rate = the rate of change (decrease) in temperature with a change in height; the average lapse rate in Troposphere = - 6.5 C / 1 km. • Inversion layer = change in the sign of the lapse rate, + 6.5 C / 1 km. • Isothermal environment = no change in temperature with height
Layers of the atmosphere as related to average profile of air temperature. Fig. 1-11, p. 13
Vertical Structure of the Atmosphere • Observation: Radiosonde • Weather balloon • Instrument and transmitter • Air temperature, humidity, pressure
Vertical Structure of the Atmosphere • The Ionosphere • Not a true layer but an electrified region within the upper atmosphere (from about 60 km to the top of the atmosphere) where fairly large concentrations of ions and free electrons exist. • Ions = molecule with an additional or minus an electron • Sun light creates layers: F(at 180 km) ,E(at 120 km),D(at 60 km) layers • Ionosphere plays a major role in AM radio communications
At night, the F region of ionosphere strongly reflects AM radio waves, allowing them to be sent over great distances. During the day, the lower D region strongly absorbs and weakens AM radio waves, preventing them from being picked up by distant receivers.
(more solar eruptions) Based on composition of the atmosphere
Weather and Climate • Weather: short term changing in air temperature, air pressure, humidity, clouds, precipitation, visibility, and wind • Climate: long term patterns and average weather; not just magnitude but also frequency Assignment 1
Weather & Climate • Meteorology • Study of the atmosphere and its phenomena • Aristotle 340 B.C. – book on natural philosophy, Meterologica. – Greek word = meteoros = “high in air” – sum of knowledge at that time The birth of Meteorology as a natural science did not take place until the invention of weather instruments: thermometer ( end of 16th century), barometer (17th century), hygrometer (18th century). • 1843 telegraph invented • 1920s concepts of air masses and fronts • 1940s upper air balloons • 1950s radar and computers • 1960s satellite
Doppler radar has the capacity of estimating rainfall intensity.
Weather & Climate • Satellite’s View • Geostationary satellite: situated at about 36,000Km (22,300mi) above the earth. Satellite travels at the same rate as the earth spins, which allows it to remain positioned above the same spot. • Meridians measure longitude (W-E): lines running from north to south. Prime meridian (00meridian) runs through Greenwich, England. • Parallels to equator (00latitude) measure latitude (N-S) • Weather maps: pressure cells, fronts, surface stations
Satellite Image: clouds+ storms at surface Fig. 1-15, p. 20
Simplified surface weather map that correlates with the satellite image shown .
Weather & Climate • Weather and Climate in Our Lives • Two general reasons for studying how weather and climate impacts our lives: economic efficiency and public safety. • Crops • Utilities • Extreme cold and heat • Tornados and hurricanes • Clothing • Meteorologist • Any person with a college degree in meteorology or atmospheric science; not just the TV weather person • Half of 9000 meteorologists employed by the US National Weather Service • Researchers and operational meteorologists
Chapters 2 and 19 Energy: Warming the earth and Atmosphere
Energy, Temperature, & Heat • Energy is the ability to do work (push, pull, lift) on some form of matter. • Potential energy is the potential for work. Gravitational potential energy: • Kinetic energy is energy of a moving object • Total energy = PE + KE • Temperatureis a measure of the average speed of atoms and molecules. • High temperature corresponds to high average speeds
Cold, more dense air Warm, less dense air
Energy, Temperature, & Heat • Which has more energy? • A lake or a cup of hot tea? • Heat is the energy in the process of being transferred from one object to another because of a difference in temperature. • First Law of Thermodynamics: Energy cannot be destroyed or created conservation of energy
Temperature Scales • Fahrenheit (early 18th century): 32 freeze, 212 boil • (180 equal divisions) • Celsius (later in the 18th century): 0 freeze, 100 boil • (100 equal divisions) • Kelvin (19 century): absolute; 0K = -273°C (no thermal motion)