The Atmosphere: Structure and Temperature

How Does Weather differ from Climate? Weather : constantly changing and it refers to the state of the atmosphere at any given time and place Climate – is based on observations of weather that have been collected over many years

Measurable Properties of Weather and Climate Air temperature Humidity Type/Amount of Precipitation Air Pressure Speed/Direction of Wind

Composition of the Atmosphere Major Components: Air – a mixture of different gases and particles Nitrogen and Oxygen makeup 99% 1 % is argon Carbon dioxide is present in small amounts but is an active absorber of energy so plays a role in heating.

Variable Components: Water Vapor Water vapor - source of all clouds and precipitation. Absorbs heat and some solar energy

Dust Particles Movements of the atmosphere allow solid and liquid particles to be suspended within it Large Particles are too heavy to stay in the air for too long Microscopic remain suspended for longer Examples: smoke, pollen

Ozone Not distributed evenly Absorbs Potential harmful UV radiation by the sun Without it our habitat would be uninhabitable

Human Influences and Primary Pollutants Primary Pollution: emitted directly from identifiable sources Transportation counts for half Secondary Pollutions: not emitted directly into air (agriculture) Can be caused by reactions

Primary Pollutants and Sources Carbon monoxides Nitrogen oxides Volatile Organics Sulfur oxides Particulate matter Sources Transportation Stationary Source Fuel Combustion Industrial Processes Solid Waste

Pressure and Temperature Changes Key Point: The atmosphere rapidly thins as you travel away from Earth until there are too few gas molecules to detect. Pressure Changes Atmospheric pressure is the weight of the air above. As you go up in altitude (or travel away from Earth) pressure decreases

Layers of the Atmosphere The Troposphere - the bottom layer Temperature decreases with an increase in altitude. Where weather occurs Tropopause: boundary of the troposphere The Stratosphere Above the troposphere Temperature remains constant, then gradually starts to increase Contains the ozone layer Stratopause: boundary of the stratosphere

The Thermosphere: Upper layer The Mesosphere Temperature decreases with height Mesopause: boundary of the mesosphere The Thermosphere: Upper layer Temperature increase with height Auroras occur here Fades into space

Earth-Sun Relationships Energy that drives the weather and climate come from the sun Solar energy is NOT distributed evenly Varies with latitude, time of day, and season of the year Unequal heating of the Earth creates wind’s and drives the ocean’s currents Results in weather

Earth’s Motion Rotation: spinning of the Earth about its axis (24 hours) Revolution : movement of Earth in its orbit around the sun (365.25 days) Key Point: Seasonal changes occur because Earth’s position relative to the sun continually changes as it travels along its orbit. Tilted 23.5 from perpendicular Rotation and Revolution

What causes Seasons? NOT IN NOTES Seasons are caused by the tilting of the earth on its axis When the Earth is tilted towards the Sun – warmer seasons When the Earth is tilted away from the Sun – cooler seasons

Summer Solstice: June 21 or 22 First day of summer “leaning” 23.5˚ towards the sun or Tropic of Cancer Winter Solstice: December 21 or 22 “leans” 23.5 away or Tropic of Capricorn

Equinox Autumnal Equinox September 22 or 23 First day of fall Spring Equinox March 21 or 22 First day of spring Sun rays directly over the equator Daylight and nighttime length are the same

Heating the Atmosphere Heat: the energy transferred from one object to another because of a direct difference in their temperature Temperature: measure of the amount of heat

Ways Heat Can be Transferred Key Point: Heat is the energy transferred from one object to another because of a difference in their temperatures. Conduction The transfer of heat through matter by molecular activity Transfer by touching Collisions

Convection The transfer of heat by a mass movement or circulation Fluids Radiation Travels out in all directions Doesn’t need matter

What happens to solar radiation? Three Results: Some energy is absorbed, causing temp to increase. Water and air are transparent to certain wavelengths (goes through) Some bounces off

What Happens to Solar Radiation? Reflection bounces off 30 % is reflected back to space Scattering Disperses light so travels in many directions.

Absorption: 50 % of the solar energy the Earth’s surface 20% is absorbed in the clouds Greenhouse effect: heating of Earth from radiation being absorbed

Why Do Temperatures Vary? A temperature control is any factor that causes temperature to vary from place to place and time to time. Factors: Heating of land Heating of water Altitude Geographic position Cloud cover Ocean currents

Land and Water Temperatures Land heats and cools more rapidly and to higher temperatures than water. Land also cools more rapidly and to a lower temperature than water.

Windward verses Leeward Winds blow from ocean to shore, so wetter Leeward: Winds blow from land toward ocean, so dry Mountains act as barriers

Altitude Higher altitudes have cooler temperatures.

Albedo the fraction of total radiation that is reflected by any surface. Key Point: many clouds have high albedo and reflect the sunlight back to space.

World Distribution and Temperatures Isotherms - lines on a weather map that connect points that have the same temperatures Hot colors near equator , cool colors toward the poles

Picture and Graph Questions Pg. 482 When do the sun’s rays strike 23.5? When does summer solstice occur in the northern hemisphere? When is the autumnal equinox occur in the southern hemisphere? Pg. 490 Is Eureka or NYC the leeward city? Which city has temperatures that are influences by ocean winds AND has cool summers and mild winters? Pg. 492 What does cloud cover do to the day time temperatures? What does cloud cover do to the nighttime temperatures?