Unit 5 Seasons and Atmosphere
Standard 1:
Revolution Motion of a body along a path around some point in space. Earth s orbit is elliptical Earth s distance from the sun varies Perihelion Earth is closest to the sun 147 million km away Occurs on January 3rd Aphelion Earth is farthest from the sun 152 million km away Occurs on July 4th
Rotation The turning or spinning of a body on its axis Causes day and night Two kinds of measurement Mean Solar Day time interval from one noon to the next (24 hours) Sidereal Day time it takes for Earth to make one complete rotation (360 ) with respect to a star other than the sun (23 hours, 56 minutes, 4 seconds)
Seasons are caused by the tilting of the earth on its axis (23.5 ) When the Earth is tilted towards the Sun warmer seasons When the Earth is tilted away from the Sun cooler seasons
Formation of the Universe The Big Bang Theory At one time, the entire universe was confined to a dense, hot, super-mass ball., About 13.7 billion years ago a violent explosion occurred, hurling this material in all directions. Marks the beginning of the universe. VIDEO LINK
Earth s Motions Precession Slight movement over a period of 26,000 years where Earth s axis points in different directions. Points to two stars Polaris Vega Current pointing to Polaris Has no affect on seasons.
Earth s Motions Nutation Oscillatory movement of the axis of a rotating body (wobble) Observed during precession Occurs about 18.6 years
Earth s Motions Barycenter The point between two objects where they balance each other. The center of mass where two or more celestial bodies orbit each other. Barycenter website with animation
The Atmosphere: Structure and Temperature
Standard 2:
Composition of the Atmosphere Main Components Nitrogen 78% Oxygen 21% CO 2 < 1% Argon < 1%
Pressure and Temperature Changes The atmosphere rapidly thins as you travel away from Earth until there are too few gas molecules to detect. Pressure Changes As you increase in altitude, or travel away from Earth, pressure decreases Temperature Changes As you increase in altitude in the Troposphere the temperature decreases. Density Changes
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 Mesosphere Above the stratosphere Temperature decreases with height Mesopause: boundary of the mesosphere The Thermosphere: Upper layer of the atmosphere Temperature increase with height Auroras occur here Fades into space
Ozone Ozone is a form of oxygen that combines three oxygen atoms into each molecule (O 3 ) Ozone filters and absorbs harmful UV radiation by the sun
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 Heat transfer from HOT to COLD objects Conduction The transfer of heat through matter by molecular activity Transfer by touching
Convection The transfer of heat by a mass movement or circulation within a substance Radiation Travels out in all directions Solar energy reaches earth by radiation
Standard 3:
Air pressure is the pressure exerted by the weight of air above Exerted in all directions (up, down, and sideways) The air pressure pushing down on an object exactly balances the air pressure pushing up on the object Average Air Pressure at sea level is 1 kg/cm 2
Barometer: device used for meaasuring air pressure Unit: millibars (mb) inches of mercury Torricelli: invented the mercury barometer in 1643
Wind is a result of horizontal differences in air pressure Air flows from areas of high pressure to areas of lower pressure.
Low Pressure Centers High Pressure Centers Centers of Low Pressure High Pressure AKA Cyclones Anti-cyclones Pressure Behavior Pressure drops Pressure increase Wind Behavior Winds blow counterclockwise Winds blow outward and clockwise Weather Associated Severe and stormy Fair and Sunny Symbol L that is RED H that is BLUE
The unequal heating of earth s surface generates pressure differences Solar radiation is the ultimate energy source for most wind
Jet streams are fast-moving rivers of air Speed: 120 and 240 kilometers per hour Direction: Westto-east direction.
The atmosphere balances itself by acting as a giant heat-transferring system Moves warm air to the poles and cool air towards the equator Coriolis Effect
Trade winds Two belts of winds that blow almost constantly from east to west Westerlies Dominate west to east motion of the atmosphere (Jet Stream occurs here) Polar easterlies Winds that blow east to west Polar front Interaction of warm and cool air masses produces a stormy belt
Direction Labeled by the direction from which they blow Ex: winds blowing from the Southeast. Tool: Wind Vane
Anemometer Measures how fast wind is blowing
Standard 4:
What is Meteorology? The study of weather, climate, and atmospheric processes
How Does Weather differ from Climate? Weather is 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 to help describe a place or region
Why Do Temperatures Vary? 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 Water heats up longer and will retain the heat longer
World Distribution and Temperatures Isotherms - lines on a weather map that connect points that have the same temperatures
Isobars lines on a map that connect places of equal air pressure A pressure gradient The spacing of isobars indicates the amount of pressure change over a given time
Closely spaced isobars: indicate a steep pressure gradient and high winds. Widely spaced isobars: indicate a weak pressure gradient and light winds.
Standard 5:
What is the significance of Water Vapor? Water vapor - source of all clouds and precipitation.
The three states of matter solid, liquid, and gas (plasma is the fourth)
amount of water vapor in air.
Ratio of the air s actual water-vapor content compared with the amount of water vapor air can hold at that temperature and pressure. Lowering air temperature causes an increase in relative humidity Raising air temperature causes a decrease in relative humidity
Instrument: Hygrometer Psychrometer : a type of hygrometer consisting of two identical thermometers mounted side by side Dry bulb: give the present air temperature Wet bulb: has thin wet wick tied around the end
Dew point is the temperature to which a parcel of air would need to be cooled to reach saturation.
Clouds are classified on the basis of their form and height.
Cirrus (cirrus = curl of hair) high, white, and thin Cumulus (cumulus = a pile) rounded individual cloud masses that have a flat base and the appearance of rising domes or towers Stratus (stratus = a layer) best described as sheets or layers that cover much or all of the sky
Clouds form when air is cooled to its dew point
Albedo the fraction of total radiation that is reflected by any surface. Daylight Cloud Cover Clouds reflect solar radiation back to space Temperatures are lower than on a clear day Nighttime Cloud Cover Clouds absorb radiation from land and reradiates some of it back to Earth Temperatures are higher than on a clear night
For precipitation to form, cloud droplets must grow in volume by roughly one million times.
The type of precipitation that reaches Earth s surface depends on the temperature profile in the lower few km of the atmosphere Rain: drops of water that fall from a cloud and have a diameter of at least 0.5 mm Snow: light, fluffy, sixsided ice crystals
Sleet: fall of small particles of clear to translucent ice Glaze: when raindrops become supercooled as they fall through subfreezing air and turns to ice when they impact objects Hail: form of solid precipitation which consists of balls of irregular lumps of ice produced in cumulonimbus clouds
A cloud with its base at or very near the ground.