Things we need to talk about: Astro Test When you can retake (By May 1!) Grades Tuesday 4/23/2012

Chapter 11

Air is a combination of many gases 78% nitrogen 21% oxygen 1 % argon, hydrogen, carbon dioxide, water vapor, and other gases The amount of water vapor varies with the seasons, altitude, and location What locations would have more water vapor? Less? Atmosphere composition

Ozone – a gas formed by the addition of a third oxygen atom to an oxygen molecule (O 2 ) Exists in small quantities in a layer above Earth’s surface Absorbs UV radiation from the Sun Ozone

Atmosphere is composed of layers Each layer differs in composition and temperature Structure of the Atmosphere

Troposphere – The layer closest to the Earth Contains most of the mass of the atmosphere Contains water vapor Most of the weather takes place here Collects air pollution Characterized by decrease in temperature from bottom to top Layers of the Atmosphere

Stratosphere – layer above the troposphere Made primarily of concentrated ozone Absorbs more UV radiation than the troposphere Air gradually increases in temperature to the top of the layer Layers of the Atmosphere

Mesosphere – Layer above the stratosphere No concentrated ozone Temperature decrease Thermosphere – Layer above the mesosphere Contains only a small portion of the atmosphere’s mass Temperature increases again (up to 1000*C) Molecules are so sparse that it would not seem warm Layers of the Atmosphere

Exosphere – The outermost layer No clear boundary between atmosphere and space Layers of the Atmosphere

Radiation – the transfer of energy through space by visible light, UV radiation, or other forms of electromagnetic waves Earth is continuously absorbing solar radiation It is also continuously sending it back into space 6% of solar rays are reflected by the atmosphere 25% is reflected by the clouds 4% is reflected by the Earth’s surface 15% is absorbed by the atmosphere 50% directly or indirectly absorbed by Earth’s surface The rate of absorption depends on the physical characteristics of the area and the amount of solar radiation it receives. Solar fundamentals

Solar radiation does not heat the air directly So how does the air become warm? Much of the solar radiation passes through the atmosphere and is absorbed by the Earth’s surface The surface then radiates energy Solar Fundamentals

Conduction – The transfer of energy that occurs when molecules collide Affects only a very thin atmospheric layer near Earth’s surface Energy is transferred from the particles of air near Earth’s surface to the particles of air in the lowest layer of the atmosphere Solar Fundamentals

Convection – the transfer of energy by the flow of a heated substance Pockets of air near the Earth’s surface are heated, become less dense that the surrounding air, and rise Once it rises, it expands and starts to cool Then it sinks and warms again Solar Fundamentals

Words you should probably know…

Temperature – a measurement of how rapidly or slowly molecules move around More molecules in a given space generate a higher temperature Measured in degrees Fahrenheit (°F), degrees Celsius (°C), or Kelvin Heat – the transfer of energy that occurs because of a difference in temperature between substances Heat always flows from an object of higher temperature to an object of lower temperature Temperature vs. Heat

Dew Point – the temperature to which air must be cooled at constant pressure to reach saturatuion Saturation – the point at which the air holds as much water vapor as it possible can Why is this important? Until air is saturated, condensation cannot occur Condensation – occurs when matter changes from a gas to a liquid Other Atmospheric Measurements

Air Pressure – the gravitational attraction between Earth and atmospheric gases Decreases with height because there are fewer particles exerting pressure Air Pressure

Wind – air moving from an area of high pressure to an area of low pressure Changes with height of atmosphere Wind

Humidity – the amount of water vapor in the air Relative humidity – the ratio of water vapor in a volume of air relative to how much water vapor that volume of air is capable of holding Relative humidity varies with temperature Warm air can hold more moisture than cool air Expressed as a percentage Problem solving lab p. 283 Humidity

HeightShape PrefixDescriptionPrefixDescription CirroHigh clouds with bases starting above 6000 meters CirrusLatin meaning: “Hair” Wispy, stringy clouds AltoMiddle clouds with bases between 2000 m and 6000 m CumulusLatin meaning: “pile or heap” Puffy, lumpy-looking clouds StratusLatin meaning: “layer” Featureless sheets of clouds StratoLow clouds below 2000 mNimbusLatin meaning: “cloud” Low, gray rain clouds Cloud Classification

Types of Clouds

Stratus Clouds – form when fog lifts away, covering much of all of the sky in a given area Cumulus – puffy, heap; can lead to moisture, thunderstorms, etc. Stratocumulus – layer of cloud clumps with thick and thin areas; found ahead or behind frontal systems Nimbostratus – generally thick, dense stratus or stratocumulus clouds producing steady rain or snow. Low Clouds

Types of Clouds

Altostratus – flat and uniform texture; frequently indicate the approach of a warm front Do not produce significant precipitation Altocumulus – heap-like clouds; may align in rows or streets of clouds Middle Clouds

Types of Clouds

Cirrus – wispy, feathery; composed of ice crystals; first sign of an approaching warm front Cirrostratus – widespread, veil-like layer Cirrocumulus – layered, lumpy clouds; may line up in rows or streets of clouds High Clouds

Types of Clouds

Cumulonimbus – puffy walls of clouds associated with thunderstorms Fog – layer of stratus clouds on or near the ground Other Clouds

Cloud Classification Chart

Precipitation – all forms of water that fall from clouds Precipitation

Water Cycle Evaporation – the process of changing from a liquid to a gas Collection – Water soaking into the ground, entering lakes, streams, oceans, falling into bodies of water Condensation – changing from a gas to a liquid Precipitation – any form of water coming from the clouds