Atmosphere: Composition, Structure, and Temperature Chapter 14

Weather and Climate a. Weather – state of the atmosphere at a particular place for a short period of time, changes hourly daily and seasonally.

Weather and Climate b. Climate – generalization of the weather conditions in a place over a long period of time.

Weather and Climate c. Elements of Weather & Climate i.Temperature ii.Humidity iii.Type and Amount of Cloudiness iv.Type and Amount of Precipitation v.Air Pressure vi.Speed and Direction of the Wind

Composition of the Atmosphere a. Major Components (Constant worldwide) i. Nitrogen – 78% ii. Oxygen – 21% iii. Argon -.93% iv. Carbon Dioxide -.04% v. Other Gases - < 1%

Composition of the Atmosphere

Variable Components i. Water Vapor 1. Varies between almost none to 4% by volume 2. Source of all clouds and precipitation 3. Absorbs heat from the Earth (latent heat) and transports it from one region to another

Variable Components ii. Dust 1. Includes microscopic particles invisible to the naked eye 2. Sources include Earth’s surface and meteors that disintegrate in Earth’s atmosphere 3. Can act as surfaces on which water vapor condenses, essential to cloud formation 4. May reflect or absorb incoming solar radiation 5. Causes colors of the sunset

Variable Components iii. Ozone 1. Form of oxygen with three oxygen molecules (O 3 ) 2. O 2 molecules are split into single atoms by UV radiation, and then collide with another O 2 molecule forming O 3. 3.Concentrated in the stratosphere kilometers above the Earth. 4. Absorbs the potentially harmful UV radiation from the sun

Height and Structure of the Atmosphere a. Pressure Changes i. Atmospheric Pressure – the weight of the air above. (1000 millibars or 1 sea level)

Height and Structure of the Atmosphere b. Temperature Changes – the atmosphere is divided into four layers based on temperature changes i. Troposphere ii. Stratosphere iii. Mesosphere iv. Thermosphere

Height and Structure of the Atmosphere i. Troposphere 1. Lowest layer, Location of weather phenomenon 2.Environmental Lapse Rate - temperature decrease in the troposphere (avg 6.5°C/km) 3.The thickness of the troposphere is not consistent worldwide, dependent on season and latitude.

Height and Structure of the Atmosphere ii. Stratosphere 1. Temperature begins to increase with height. 2. The atmosphere’s ozone is concentrated in this area

Height and Structure of the Atmosphere iii.Mesosphere 1.Decreasing temperature with height 2.Approaches -90°C at 80 kilometers above Earth’s surface.

Height and Structure of the Atmosphere iv. Thermosphere 1. No well-defined upper limit 2. Increasing temperature > 1000°C

Layers of the Atmosphere

STOP! NOTES WILL CONTINUE TUESDAY WHEN MRS LAFEVER GETS BACK! Complete the Layers of the Atmosphere assignment and turn it in. The instructions are a class set, please return them to the basket when you’re done. Answer the questions on the back of your graph. Put away all supplies (coloring pencils, rulers, etc) BEFORE you leave.

Earth- Sun Relationships a. Earth’s Rotation and Revolution i. Rotation – the spinning of the Earth about its axis once every 24 hours. ii. Revolution – movement of the Earth in its orbit around the 107, 000 km /hour.

Earth- Sun Relationships b. Seasons i. Causes of Seasons – Seasonal variation in the altitude of the sun due to the inclination of the axis affects the amount of energy received at Earth’s surface in two ways.

Earth- Sun Relationships 1. The lower the angle the more spread out and less intense is the solar radiationthat reaches the surface.

Earth- Sun Relationships 2. The angle of the sun determines the amount of atmosphere the rays must penetrate. The longer the path through the atmosphere, the greater the chance for absorption, reflecting and scattering.

Seasons

Earth- Sun Relationships ii. Solstices and Equinoxes – (Northern Hemisphere) 1. Summer Solstice – (June 21-22) Vertical rays of the sun at 23 ½ degrees north latitude, called the Tropic of Cancer. Length of daylight is greater than darkness. 2. Winter Solstice – (December ) Vertical rays of the sun at 23 ½ degrees south latitude, called the Tropic of Capricorn. Length of night is longer than daylight.

Earth- Sun Relationships ii. Solstices and Equinoxes – (Northern Hemisphere) 3. Autumnal Equinox – (September 21-22) Vertical rays of the sun strike 0 degrees latitude, the equator. Length of daylight is 12 hours, and night is 12 hours. 4. Spring Equinox – (March 21-22) Vertical rays of the sun strike 0 degrees latitude, the equator. Length of daylight is 12 hours, and night is 12 hours.

Mechanisms of Heat Transfer a. Conduction – the transfer of heat through matter by molecular activity. b. Convection – The transfer of heat by the movement of a mass or substance from one place to another.

Mechanisms of Heat Transfer c. Radiation – Mechanism of heat transfer that can transmit heat through the relative emptiness of space. i. All object emit radiant energy, hotter objects radiate more total energy. ii. The hotter the radiating body the shorter the wavelength 1. Sun – λ=0.5 micrometers (visible light) short-wave radiation 2. Earth – λ=10 micrometers (infrared/heat range) long-wave radiation

Mechanisms of Heat Transfer c. Radiation – Mechanism of heat transfer that can transmit heat through the relative emptiness of space. iii. The gases in the atmosphere are selective absorbers and radiators. Earth’s atmosphere is relatively transparent to visible light but an efficient absorber of infrared.

Conduction, Convection and Radiation

Paths Taken by Incoming Solar Radiation a. Scattering - redirection of solar radiation by gases and dust particles.

Paths Taken by Incoming Solar Radiation b. Albedo – fraction of the total radiation that is reflected by a surface. Earth’s albedo is approximately 30% though it can vary at different times, places, cloud cover, and particles in the air.

Albedo

Paths Taken by Incoming Solar Radiation c. Absorption i. Nitrogen is a poor absorber of all types of incoming radiation. ii. Oxygen and ozone are efficient absorbers of ultraviolet light. iii. Water vapor is the only other significant absorber of solar radiation.

Heating the Atmosphere: The Greenhouse Effect a. Approximately 50% of the solar energy that strikes the atmosphere reaches Earth’s surface and is absorbed. Most of this is then reradiated skyward.

Heating the Atmosphere: The Greenhouse Effect b. Water vapor absorbs 5x more terrestrial radiation than any other gas and is responsible for the warmer temperatures in the troposphere. The atmosphere is heated from the ground up.

Temperature Measurement and Data a. Daily Mean Temperature – add the maximum and minimum temperatures and divide by two. b. Daily Temperature Range – difference between the maximum and minimum daily temperatures. c. Monthly Mean Temperature – add together daily means for the month then dividing by the # of days.

Temperature Measurement and Data d. Annual Mean Temperature – average of the twelve monthly means. e. Annual Temperature Range – difference between the highest and lowest monthly means.

Temperature Measurement and Data

Controls of Temperature a. Land and Water – land heats more rapidly and to higher temperatures than water and cools more rapidly and to lower temperatures than water. i. Water has a larger specific heat than land. ii. Since water is transparent heat penetrates further than on land. iii. Water circulates distributing heat through greater mass. iv. Evaporation is greater from water than from land.

Controls of Temperature b. Altitude c. Geographic Position d. Cloud Cover and Albedo

World Distribution of Temperature a. Isotherms – lines that connect places of equal temperature. i. Generally trend east/west and show a decrease in temperature pole ward from the tropics. ii. Straighter and more stable in the Southern Hemisphere