Introduction+to+Meteorology+(chapters+16-20)

=Big Idea: Atmosphere plays a part in shaping the Earth's surface.=

Essential Questions:

 * 1) ====How does the movement of the Earth create the seasons?====
 * 2) How is climate change altering the surface of the Earth?
 * 3) How is weather created?
 * 4) What roles has man played in climate change?

Earth Science Standards: 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.8

=Question of the Day: What is the difference between weather and climate?=

=Weather and Climate=
 * Weather is the day to day changes in the atmosphere whereas climate is the sum of all weather data over a period of time. Weather can change from hour to hour while climate is constant year from year. Weather can't be predicted because it is chaotic and is constantly changing. Saying here in New England is, "If you don't like the weather, wait a minute!"
 * Elements of weather are qualities and properties that are measured regularly like air temperature, humidity, cloud coverage, precipitation, air pressure, and wind speed and direction.
 * Weather stations report the conditions at that station at that time and information helps to make a weather map that can be used by forecasters to predict the weather. [[image:whs-earthscience/weathermap.jpg width="480" height="345"]]
 * Stations use symbols to relay a large quantity of information otherwise the weather map would be jumbled and hard to read.
 * [[image:stationcode.jpg width="305" height="282"]]

=The Atmosphere= =Atmospheric Heating=
 * Air is the horizontal movement that happens from an area of high pressure to an area of low pressure.
 * The most abundant gas in the atmosphere is Nitrogen at 78%, Oxygen is 21%, and Carbon dioxide is .035%.
 * Other components in the air that can change are
 * Water vapor- has the ability to absorb heat. Forms clouds and precipitation.
 * Dust- known as aerosols. Needed to form clouds (condensation nuclei). Able to absorb, reflect, and scatter light. Responsible for the colors seen during a sunrise or sunset.
 * Ozone- is the formation of 3 oxygen molecules; responsible for absorbing solar radiation in the form of Ultraviolet radiation.
 * Air pressure is caused due to the weight of the atmosphere upon earth because of gravity. Sea level has around 1000 millibars (mb) of pressure which is about 14.7 pounds per square inch. Pressure decreases with the increase of altitude because the density of the air decreases.
 * Layers of the atmosphere are based upon temperature.
 * Troposphere is the layer closest to the earth. Here is where all weather happens. The thickness varies with location (latitude) and season. The environmental lapse rate (ELR) is a measurement of how the temperature decreases with increase in altitude. The ELR is 6.5F for every 1000m (1 Km) or 3.5 F for every 1000feet. The air becomes thinner as you get higher in the troposphere. 50% of the atmosphere is found within 3.5 miles of the earth's surface and 90% of the atmosphere is found within 10 miles of the earth's surface.The layer that separates the troposphere from the next sphere is called the tropopause.
 * Stratosphere is the layer above the troposphere. It's located from 12 km to 50 km above the earth. The temperature is pretty constant then gradually increases as it continues into the stratopause, layer that separates the stratosphere from the mesosphere. Upper area of the stratosphere contains the Ozone layer (layer created by the combination of 3 oxygen molecules). This layer absorbs solar radiation in the form of ultraviolet radiation hence the cause for the increase of temperature past the 20 Km mark.
 * Mesosphere is the third layer from the earth's surface. Here temperature decreases with height until it reaches the mesopause, layer that separates the mesosphere from the thermosphere. This area has the coldest temperatures of all the layer. Ice crystals are found within this region. This is where Meteor showers happen because the ice crystals cause friction against an incoming meteoroid and burns it up producing the meteor, streak of light across the sky.
 * Thermosphere is the last layer of atmosphere. This area has no defined upper-limit. Temperatures increase within this area because of the solar radiation. The area is divided into two parts: the ionosphere and the exosphere. The exosphere is the upper-limit region where satellites orbit and the ionsphere is where the Auroras (Northern and Southern lights) happen because high energy particles from the sun's solar wind comes in contact with the high moving gas molecules producing the wonderful colors in the upper atmosphere.
 * [[image:TGA305t.jpg width="560" height="420"]]
 * [[image:TGA305t.jpg width="560" height="420"]]
 * Heat always transfers from a hot object to a cold object.
 * Mechanisms for transferring heat are
 * Conduction: direct transfer of heat from one object to another. Good conductors are metals. Good insulators are wood, glass, plastic.
 * Convection: transfer of heat due to unequal heating of a fluid via convection currents.
 * Radiation: transfer of heat via the ElectroMagnetic Spectrum (radiation) and happens in a vacuum. Like on a cold winter day, the inside of a car is warmer than the outside due to the solar radiation through the winds of the car
 * .[[image:TGA310t.jpg width="400" height="300"]]
 * Incoming Solar Radiation
 * Only 50% of the solar radiation that enters the atmosphere is absorbed by the Earth's surface.
 * The atmosphere helps to scatter, reflect, and absorb the other percentage of solar radiation.
 * [[image:TGA312t.jpg width="480" height="360"]]
 * The troposphere is heated by the absorbed solar radiation that radiates from the Earth's surface.
 * [[image:TGA313t.jpg width="480" height="360"]]

=Earth-Sun Relations=
 * Revolution is the path an object takes around the sun. 1 revolution is a year for that planet. Earth's year is technically 365.26 days. Leap year happens every 4 years.
 * Rotation is the path an object takes around its axis. I rotation is a day for that planet. Earth's day is technically 23.56 hours.
 * Seasons are due to the earth's tilt (23.5 degrees on its axis) and its revolution. Because of these, it results in the changing of the sun angle hitting the earth's surface and the length of daylight. [[image:TGA307t.jpg width="480" height="360"]]
 * Solstice translates into Sun Stop. This is the point in the sky that the sun stops rising/lowering. The Summer Solstice is the longest day of the year in the Northern Hemisphere. The solstice happens in June. Though the earth is the furthest from the sun in its revolution, since the North Pole is facing the sun, more solar radiation hits the equator and above. The Winter Solstice is the shortest day of the year in the Northern Hemisphere. The solstice happens in Dec. Though the earth is the closest to the sun in its revolution, the North Pole is away from the sun causing solar radiation to hit the equator and below.
 * Equinox is that period in which the amount of daylight is equal to night. The sun is hitting the equator directly at a 90 degree angle and radiation is projected to both the North and South latitudes. The Vernal (Spring) equinox happens in March and the Autumnal (Fall) equinox happens in September.
 * [[image:TGA308t.jpg width="560" height="420"]]
 * [[image:TGA309t.jpg width="560" height="420"]]

=Temperature=
 * Isotherms are lines drawn on a map that connect areas of the same surface temperature.
 * [[image:TGA314t.jpg width="560" height="420"]]
 * Human perception of temperature is based upon air temperature, relative humidity, wind, and solar radiation.
 * Controls of temperature is mainly latitude (amount of solar radiation hitting the surface of the earth). But other controls are
 * Differential heating of land and water: Land heats and cools faster than water because water has a higher specific heat.
 * Altitude: temperature decreases with altitude (Environmental Lapse Rate) due to the change in density of the atmosphere as altitude increases.
 * Geographic position: Where are you located? Are you at the equator (0 degrees latitude) or at the poles (90 degrees latitude North or South)? Are you along the coast or inland? Closer to the equator is hotter because of more solar radiation than at the poles. Closer to the coast it is cooler because of the water than inland.
 * [[image:TGA306t.jpg width="480" height="360"]]
 * [[image:TGA315t.jpg width="480" height="360"]]
 * [[image:TGA316t.jpg width="480" height="360"]]
 * Cloud Cover: how much is the sky covered with clouds? If there are lots of clouds, heat will not be able to radiate back into space at night so it is warmer then when there are no clouds. During the day, more clouds prevents solar radiation from hitting the surface so it is cooler than if there were not clouds.
 * [[image:TGA317t.jpg width="560" height="420"]]
 * Surface albedo: light that is reflected off of material. On the water, light reflects more than on a paved driveway. Fresh snow reflects more light than dirty snow.
 * Measurements of temperature are taken with a thermometer. Different types of data are collected and are used by meteorologist and climatologist.
 * Daily maximum-highest temperature in 24 hours.For example:75F
 * Daily minimum-lowest temperature in 24 hours. For example:35F
 * Daily mean temperature-add the daily max and daily min and divide by 2. For Example: 75F+35F= 110F/2=55F.
 * Daily range- Subtract the Daily min. from the Daily max. For example: 75F-35F=40F
 * Monthly mean- add up all the daily mean temperatures and divide by the number of days in that month.
 * Annual mean-add up all the monthly means for the year and divide by 12.
 * Annual temperature-Subtract the lowest monthly mean from the highest monthly mean (this is usually the mean for July and Jan).

=World Distribution of Temperature=
 * Temperature Maps are used to show annual temperature for the world by using isotherms.
 * Global patterns are seen when viewed.
 * Temperature decreases as you go from the equator to the poles.
 * Isotherms exhibit a latitudinal shift with the seasons.
 * Warmest and coldest temperatures occur over land.
 * In the Southern Hemisphere, isotherms are straighter and more stable than the Northern Hemisphere because the Southern Hemisphere has less land.
 * Isotherm also show ocean surface currents.
 * [[image:TGA318t.jpg width="560" height="420"]]
 * [[image:TGA319t.jpg width="560" height="420"]]

=States of Matter (Physics Review)=
 * There are 3 major states of matter: solid, liquid, and gas. Another state of matter is plasma.
 * To change from one state of matter to another, heat must be absorbed or released.
 * Heat energy is measured in calories. A calorie is the amount of heat energy needed to raise the temperature of 1 g of water 1 degree C.
 * Latent heat is heat that is stored or hidden.
 * Process of matter
 * Evaporation-liquid coverts into a gas because heat (600 calories) is added. This is known as the latent heat of vaporization.
 * Condensation-gas converts into a liquid because heat (600 calories) is released. This is known as the latent heat of condensation.
 * Melting-solid to a liquid because heat (80 calories) is added. This is known as the latent heat of melting.
 * Freezing-liquid to a solid because heat (80 calories) is released. This is known as the latent heat of fusion.
 * Sublimation-solid to a gas because heat (680 calories) is added. This happens to dry ice or to ice in a freezer.
 * Deposition-gas to a solid because heat(680 calories) is released. This is what causes frost in a freezer; Water vapor in the air is quickly cooled into a solid forming frost.
 * [[image:TGA320t.jpg width="560" height="420"]]

=Humidity=
 * Humidity is the amount of water vapor that is added to the air. Saturated air is air that is filled with water vapor to capacity. Think of it like a sponge. A dry sponge can absorb a lot of water until it is complete saturated, won't absorb anymore water. The only way to get more water in the sponge, is to wring it out. When the air is saturated, it can't hold any more water vapor via evaporation/transpiration until it gets rid of the water vapor that is in the air (rain storm).
 * Humidity is measured with a psychrometer and hygrometer. The psychrometer has two thermometers. One thermometer has a 'sock' over the bulb and this sock is lightly dampened with water. The other thermometer doesn't have a 'sock' over the bulb. The psychrometer is then rotated for a period of time until the wet bulb (one with the sock) stabilizes. Both the wet bulb and the dry bulb is read and a measurement called Relative Humidity can be found.
 * Specific humidity is the amount of water vapor in a given mass of air.
 * Relative humidity is the ration of water vapor in the air to how much the air can hold. This is expressed in % and can change if you add/subtract moisture or change air temperature.[[image:whs-earthscience/TGA323t.jpg width="560" height="420"]]
 * Dew point is the temperature at which air is saturated (can't hold any more water vapor) and the relative humidity is 100% and is condensed.
 * Relative Humidity is higher in the morning because (1) more water vapor has been added later the day before when temperature was higher and (2) because the temperature is cooler.

=Adiabatic Heating and Cooling=
 * Adiabatic temperature changes when air is either compressed or it expands.
 * There are different adiabatic rates: DAR and WAR
 * Dry Adiabatic Rate (DAR) is associated with unstable air. The rising air will expand and cools at a rate of 1 degree C for every 100 meters. Descending air will compress and warm at the same rate.
 * Wet Adiabatic Rate (WAR) begins once an air parcel meets the Condensation level, altitude at which Dew Point is met and clouds form. The air will continue to rise but heat is being released by the condensing of water and it causes parcel of air to cool at a rate of .5 to .9 degrees C per 100 meters.
 * [[image:TGA324t.jpg width="480" height="360"]]

=Stability of Air=
 * There are 2 types of air
 * Stable air is air that resist vertical displacement because it is cooler and more dense than the surrounding air/environment so the air wants to sink and resists rising.
 * Unstable air is air that rises because it is warmer and less dense than the surrounding air/environment. This air will continue to rise until it reaches an altitude with the same temperature.
 * There are processes that can lift air.
 * Orographic lifting happens when an elevated terrain (mountain ranges/buildings) causes air to be pushed up to the Condensation level. This will cause rain to fall on the windward side of the terrain and as air sinks down the leeward side, it will create rain shadow deserts, areas that lack moisture because the air is a dry parcel and doesn't contain moisture.
 * Frontal Wedging happens with a cold front wedges a warm front and forces the warm front air to rise.
 * Convergence is when two air masses meet and rise to upper levels.
 * Local Convection happens when air is heated at the earth's surface and rises.
 * [[image:TGA330t.jpg width="480" height="360"]]

=Cloud Formation=
 * Clouds form due to the condensing of water vapor into millions of water droplets or ice crystals. In order for clouds to form there must be condensation nuclei (dust, ash, smoke, aerosols) for the water vapor to cling to. When air is forced up in altitude it will reach the Condensation Level, area in which the air parcel reaches the dew point temperature and water vapor condenses. This is where clouds start to form.
 * Clouds are classified based upon their form and their height.
 * Form: Cirrus clouds are thin, wispy clouds. Cumulus clouds are clouds that are globular and fluffy like cotton balls. Stratus clouds are sheets and grey and cover large sections of the sky if not the entire sky.
 * Height: High clouds are above 6000m. Middle clouds are between 2000-6000 m and has the prefix "Alto" associated with them. Low clouds are below 2000m.
 * Clouds of Vertical development are clouds that begin as a low height cloud but become a high height cloud (IE: Thunderstorm clouds).
 * [[image:TGA332t.jpg width="560" height="420"]]
 * Fog
 * Fog is an atmospheric hazard. It mainly forms due to radiation cooling or when air moves over a cold surface.
 * There are different types of fog.
 * Advection fog happens when warm moist air moves over a cool surface.
 * Radiation fog happens when the Earth's surface cools quickly.
 * Upslope fog happens when humid air moves up a slope and condenses.
 * Steam fog happens when cold air moves over warm water and moisture is added to the air. Takes on the appearance of steam.
 * Precipitation fog happens when warm air moves over colder air causing precipitation and the rain evaporates quickly.
 * Precipitation
 * Forms either due to the Bergeron process or due to the Collision-Coalescence process.
 * Bergeron process happens when water vapor condenses in a cloud and freezes forming snow because the cloud has a colder temperature at a high altitude. Either the snow falls to the ground or melts on the way down to from rain.
 * [[image:TGA333t.jpg width="480" height="360"]]
 * Collision-Coalescence process happens when water droplets attract to each other and form a large droplet. This large droplet falls due to gravity and collides with other droplets breaking into smaller and more droplets. If the air temperature says warm it will fall as rain but if the air temperature below the cloud is cold, it will freeze as it falls.
 * [[image:TGA334t.jpg width="480" height="360"]]
 * There are 7 different types of precipitation: rain, drizzle, snow, sleet, glaze, hail, and rime.

=Wind=
 * Wind is the horizontal movement of air out of a high pressure area to a low pressure area. It is controlled by pressure gradient force, the Coriolis effect, and friction at the earth's surface.
 * Coriolis effect is the apparent shift in the pathway of an object/fluid above the earth's surface due to the earth's rotation
 * [[image:TGA341t.jpg width="560" height="420"]]
 * Isobars are lines on a weather map that connect areas of equal pressure (barametric pressure). If isobars are close together, there is strong wind in the area.
 * Winds are normally named from the direction in which they came from.
 * There are 2 different types of wind: local and global.
 * Local winds are caused by temperature differences and only affect a small scale area. They can change direction throughout the day. Examples are sea breezes and land breezes. During the day, water takes a long time to heat up so a high pressure system is over the water whereas a low pressure system is over the land because land heats up faster than water. This causes cool, moist air to head toward the land. At night the wind reverses direction. Other examples of local winds are valley/mountain breezes, and Chinook/Santa Ana winds.
 * [[image:TGA349t.jpg width="480" height="360"]]
 * [[image:TGA350t.jpg width="480" height="360"]]
 * Global winds are winds that are caused by global pressure patterns. These affect a larger scale area and rarely change direction. Tradewinds are found within the tropics (0-30 degrees north and south latitudes) and come from either the Northeast direction or the Southeast direction; these are warm winds. Prevailing Westerlies come from the west and are found between 30-60 degrees North and South latitudes. Our weather here in the US is affected because of these winds. Polar Easterlies always come from the East and are found in areas 60-90 degrees north and south latitudes. These are cold winds. The jet streams are also a global wind but they are located in the lower stratosphere and always travel West to East.
 * [[image:TGA345t.jpg width="480" height="360"]]

=Air Masses=
 * Large body of air with similar temperature and moisture content at any given altitude.
 * Classified based upon Nature of the surface of the source region and the latitude of the source region.
 * Nature of surface
 * Continental (c)- means the air mass originated over land. This will normally be dry air (less moisture in air).
 * Maritime (m)- means the air mass originated over water. This will normally be moist air (more moisture in air).
 * Latitude of Region
 * Polar (P)- means air originated in upper latitudes. This will normally be cool/cold air.
 * Tropical (T)- means air originated in lower latitudes. This will normally be warm/hot air.
 * 4 basic types of air masses are cT (continental Tropical), cP (continental Polar), mT (maritime Tropical), and mP (maritime Polar).
 * [[image:TGA352t.jpg width="560" height="420"]]

=Fronts=
 * Boundaries between air masses are called fronts. The air masses retain their identities and warmer, less dense air is forced upwards while cooler, dense air acts like a wedge.. These fronts influence the weather in a region and across the US.
 * Different types of Fronts:
 * **Warm Front**: Warm air replaces cooler air. Seen on a weather map with semicircles in direction front is moving. This front moves forward slowly and there is light to moderate precipitation associated with this type of front. After the front passes, there is gradual temperature increase.
 * [[image:TGA355t.jpg width="560" height="420"]]
 * **Cold Front:** Cold air replaces warm air. Seen on a weather map with triangles in direction front is moving. This front moves faster than a warm front and the weather is more violent( intensity of precipitation is greater and duration is shorter). Weather behind the front is cooler and clear skies.
 * [[image:TGA356t.jpg width="480" height="360"]]
 * **Stationary Front**: Two air mass collide and movement of air flow at front is almost parallel. The front doesn't move so there is prolonged period of precipitation until movement happens. Seen on a map with semicircles on one side and triangles on the other side.
 * [[image:stationaryfront2.jpg]]
 * **Occluded Front:** A fast moving cold front overtakes a warm front forcing the warm front up (frontal wedging). Seen on a map as both semicircle and triangles in the same direction. Weather is complex with these type of fronts and precipitation that happens is because of the warm front being forced aloft.
 * [[image:TGA358t.jpg width="480" height="360"]]