Chapter 16 Notes - ES 101 PDF

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Summary

Kevin Koch
The Atmosphere, Composition, Structure, and Temperature...

Description

Weather and Climate ● Weather - the state of the atmosphere at any given time ● Climate - a description of aggregate weather conditions; the sum of all statistical weather information that helps describe a place or region ○ “Average weather” ○ Climate data cannot predict the weather ● Elements - w/ respect to weather and climate, quantities or properties of the atmosphere that are measured regularly and that are used to express the nature of weather and climate ○ Most important elements: ■ Air temperature ■ Humidity ■ Type and amount of cloudiness ■ Type and amount of precipitation ■ Air pressure ■ Speed and direction of wind

Composition of the Atmosphere ● Air - mixture of many discrete gases, of which nitrogen and oxygen are most abundant and in which varying quantities of tiny solid and liquid particles are suspended ○ CO2 is an efficient absorber of energy emitted by Earth and influences heating of the atmosphere ● Aerosols - tiny solid particles suspended in the atmosphere ○ Act as surfaces on which water vapor can condense ○ Can absorb, reflect, and scatter among radiation ○ Can contribute to optical phenomenon -- varied hues of red and orange at sunrise and sunset ● Ozone - a molecule of oxygen that contains three oxygen atoms ○ Concentrated in the stratosphere

○ Absorbs much of the potentially harmful ultraviolet (UV) radiation from the Sun ○ Pollutant when produced at ground level b/c it can damage vegetation and be harmful to human health

Vertical Structure of the Atmosphere ● Air temperature drops with increasing height ● Troposphere - The lowermost layer of the atmosphere. It is generally characterized by a decrease in temperature and weight. ○ Region where air “turns over” ● Environmental lapse rate - The rate of temperature decreases with increasing height in the troposphere. ● Radiosonde - A lightweight package of weather instruments fitted with a radio transmitter and carried aloft by a balloon. ○ Outer boundary of troposphere is the tropopause ● Stratosphere - The layer of the atmosphere immediately above the troposphere, characterized by increasing temperatures with height, due to the concentration of the ozone. ● Mesosphere - The layer of atmosphere immediately above the stratosphere and characterized by decreasing temperatures with height. ● Thermosphere - The region of the atmosphere immediately above the mesosphere and characterized by increasing temperatures due to absorption of very shortwave solar energy by oxygen.

Earth-Sun Relationships ● Rotation - The spinning of a body, such as Earth, about its axis. ● Circle of illumination - The great circle that separates daylight from darkness. ○ When the Sun is directly overhead (at a 90° angle), the solar rays are most concentrated and thus most intense.

○ The angle of the Sun is directly overhead, the rays strike the atmosphere at a 90° angle and travel the shortest possible route to the surface. ● Inclination of the axis - The tilt of the Earth’s axis from the perpendicular to the plane of Earth’s orbit. ● Tropic of Cancer - The parallel of latitude, 23 ⅓ ° north latitude, marking the northern limit of the Sun’s vertical rays. ● Summer solstice - The solstice that occurs on June 21-22 in the Northern Hemisphere and on December 21-22 in the Southern Hemisphere. ● Tropic of Capricorn - The parallel of latitude, 23 ⅓ ° south latitude, marking the southern limit of the Sun’s vertical rays. ● Winter solstice - The solstice that occurs on December 21-22 in the Northern Hemisphere and on June 21-22 in the Southern Hemisphere. ● Autumnal (fall) equinox - The equinox that occurs on September 21-23 in the Northern Hemisphere and on March 21-22 in the Southern Hemisphere. ● Spring equinox - The equinox that occurs on March 21-22 in the Northern Hemisphere and on September 21-23 in the Southern Hemisphere. ○ Length of daylight versus darkness is determined by Earth’s position in orbit ○ During an equinox, the length of daylight is 12 hours everywhere on Earth b/c the circle of illumination passes directly through the poles, thus dividing the lines of latitude in ½ .

Energy, Heat, and Temperature ● Heat - The kinetic energy of random molecular motion ○ Used synonymously w/ thermal energy ● Temperature - A measure of the degree of hotness or coldness of a substance; a measure of the average kinetic energy of individual atoms or molecules of a substance. ○ Heat is transferred from warmer to cooler objects ○ The flow of energy can occur in three ways: conduction, convection, and radiation

● Conduction - The transfer of heat through molecular activity. Energy is transferred through collisions from one molecule to another. ● Convection - The transfer of heat by the movement of mass or substance. It can take place only in fluids. ● Radiation - The transfer of energy (heat) through space by electromagnetic waves. Along with conduction and convection, it is a mechanism of heat transfer. The term can also refer generally to electromagnetic radiation. ● Electromagnetic radiation - Transfer of energy in the form of light and related types of radiation, including gamma rays, x-rays, ultraviolet light, infrared light, microwaves, and radiowaves. ● Visible light - Radiation with a wavelength from 0.4 to 0.7 micrometer ○ Often referred to as “white” light b/c it appear “white” in color ● Infrared - Radiation with a wavelength from 0.7 to 200 micrometers ● Ultraviolet (UV) - Radiation with a wavelength from 0.2 to 0.4 micrometer ○ Laws of Radiation: ■ All objects, at whatever temperature, emit radiant energy. ■ Hotter objects radiate more total energy per unit area than colder objects. ■ Hotter objects radiate more energy in the form of short-wavelength radiation than do cooler objects. ■ Objects that are good absorbers of radiation are good emitters as well.

Heating the Atmosphere ● Reflection - The process whereby light bounces back from an object at the same angle at which it encounters a surface with the same intensity. ● Scattering - The redirecting (in all directions) of light by small particles and gas molecules in the atmosphere. The result is diffused light. ● Albedo - The reflectivity of a substance, usually expressed as a % of the incident radiation reflected.

● Diffused light - Solar energy scattered and reflected in the atmosphere that reaches Earth’s surface in the form of diffuse blue light from the sky. ● Selective absorbers - gases that absorb and emit radiation only in certain wavelengths ● Greenhouse effect - The transmission of short-wave solar radiation by the atmosphere, coupled with the selective absorption of longer-wavelength terrestrial radiation, especially by water vapor and carbon dioxide.

Air Temperature Data ● Daily mean temperature - The mean temperature for a day, which is determined by averaging the hourly readings or, more commonly, by averaging the maximum and minimum temperatures for a day. ● Daily range - The difference between the maximum and minimum temperatures for a day. ● Monthly mean - The mean temperature for a month that is calculated by averaging daily means. ● Annual mean - With respect to air temperature, the average of the 12 monthly temperatures means. ● Isotherm - a line connecting points of equal temperature ● Temperature gradient - The amount of temperature change per unit of distance

The Controls of Temperature ● Temperature control - A factor that causes temperature to vary from place to place or from time to time ○ Land heats more rapidly and to higher temperatures than water, and it cools more rapidly and to lower temperatures than water. ● Specific heat - the amount of heat needed to raise 1 gram of a substance 1° at sea level atmospheric pressure

● Windward coast - A coast where the prevailing winds blow from the ocean toward the land. ● Leeward coast - A coast where the prevailing winds blow from the land toward the ocean....