Presentation on theme: "The Study of Atmosphere and its Processes"— Presentation transcript:
1The Study of Atmosphere and its Processes MeteorologyThe Study of Atmosphere and its Processes
2Weather vs. ClimateWeather is the day-to-day atmospheric conditions in a specific time and place. Climate is the average weather conditions in a specific location over a long period of time. To be classified as climate the weather conditions are usually recorded over a 30 year period.
3History of the Atmosphere Like everything else in the natural universe, Earth’s atmosphere has been continually evolving since its birth approximately 4.6 billion years ago. It is theorized that Earth is now in its fourth major atmosphere.
4Earth’s First Atmosphere Earth’s first atmosphere was believed to be composed mainly of hydrogen and helium. However, due to Earth’s small size and low gravitational pull, scientists suggest that the gases were not able to be held in place and were simply lost to space.
5Earth’s Second Atmosphere As Earth grew in size and mass so did its gravitational pull. The second atmosphere is believed to be composed mainly of CO2, Sulfur Dioxide (SO2), H2O vapor, and Nitrogen (N2) that came from the “outgassing” of volcanoes that covered Earth’s newly formed crust.
6Earth’s Third Atmosphere In this atmosphere it is theorized that cyanobacteria multiplied, converting a CO2 rich atmosphere into a oxygen rich atmosphere. In this new atmosphere, single cell organisms would have begun to evolve into more advanced multicellular organisms. The biodiversity of life on our planet began.
7Fourth AtmosphereThe fourth atmosphere is our atmosphere. Our atmosphere is composed of two classes of gases: Permanent Gases which remain relatively constant and Variable gases which are mainly associated with atmospheric cycles.
8Earth’s Permanent Gases Some of earth’s atmospheric gases are considered to be permanent because their percentages are stable and constant. The three main gases include:Nitrogen – 78%Oxygen %Argon %
9Variable GasesSome of Earth’s gases are considered to be variable because they are constantly changing in cycles. The main variable gases include: 1. Water Vapor - .25% (Hydrologic Cycle) 2. Carbon Dioxide % (Carbon Cycle) 3. Ozone - .01% 4. Methane - .01% (normal level, currently1.7%)
10AerosolsAerosols are Small solid particles and liquid droplets in the air. (Not including: water vapor and precipitation) Forms from natural and human processes In a normal human breath, our lungs takes in approx cm3 ,(1 Liter), of air. As a result, approx. 1 million aerosols are taken into our lungs several times a minute, or about 2 tablespoons of solids each day. Condensation Nuclei: Necessary for Cloud formation, and precipitation to form.
11Layers of the Atmosphere There are 4 main layers of Earth’s atmosphere.ThermosphereMesosphereStratosphereTroposphere
12Thermosphere 1. Lowest layer: Nitrogen The thermosphere is the fourth and highest layer of our atmosphere. The thermosphere begins at approximately 90 km above the surface and ends at 2400 km. The thermosphere is divided into 4 sub-layers.1. Lowest layer: Nitrogen2. Ionosphere: Layer of charged particles. (Auroras)3. Middle layer: Helium4. Highest Layer: Hydrogen
13MesosphereThe third layer is the mesosphere. This layer is at an altitude of 50 to 90 km above the surface.
14StratosphereThe second layer is the stratosphere. This layer is at an altitude of 16 to 50 km above the surface. Located within this layer is the ozone layer. The ozone layer protects earth’s surface from excessive ultraviolet solar radiation by converting UV radiation into heat.
16TroposphereThe first layer of the atmosphere is the Troposphere which is 0 – 16 km thick at the equator and only 0 – 9km at the poles) The troposphere accounts of 80% of the total atmosphere. All life on Earth in contained within the troposphere.
18Earth’s Energy Balance In order for Earth to maintain its stable temperature, 100% of the incoming solar radiation must be balanced with an equal amount of outgoing energy. A mere 100 F change in temperature up or down could melt the ice caps and raise ocean levels 200 ft or send Earth into an ice age with glaciers covering 70% of the surface.
21Earth’s Major Air Masses Air masses are large bodies of air in the lower troposphere which have similar characteristics throughout. Types of air masses: cA – Continental Arctic – Very Cold and Dry cP – Continental Polar – Cold and Dry cT – Continental Tropical – Hot and Dry mP – Maritime Polar – Cool and Moist mT – Maritime Tropical – Warm and Moist
27H High Pressure Systems Coriolis Effect deflects air to the right in the northern hemisphereWinds rotate clockwise in the northern hemisphere (Anticyclone)High pressure systems blow cool, dry air from the upper atmosphere down toward the surfaceH
29L Low Pressure Systems Low pressure systems rotate Counterclockwise in the northern hemisphere. (Cyclone)Low pressure system draw warm moist air from the surface and blow up into the upper atmosphere where it cools and condenses from a gas to a liquid.L
32FrontsA Front is the boundary that separates two opposing air masses. Symbol Key:
33Cold FrontA Cold Front is the boundary between an advancing cold air mass and the warmer air mass it is displacing.Characteristics of a cold front: Fast moving: Average speed mphNormally in a steep wedge shapeCloud cover will usually be cumuliformAssociated with heavy precipitationsDramatic decrease in temperature: 10 degrees or moreHigh winds
35Warm FrontA Warm Front is the leading edge of advancing warm air that rises above the denser cold air mass in a process known as overrunning.The wedge shape is much more gradual than a cold front.Signs of an approaching warm front:1. Fair weather2. Cloud Formation3. Associated with light steady rain
37Stationary FrontA stationary front is a non-moving boundary between a cold front and a warm front.If there is no movement of air masses in a three hour period, then the front is considered stationary.
39Occluded FrontSince cold fronts move twice as fast as a warm front, the warm front is typically overtaken by the cold front. When this occurs, warm air gets trapped and forced upward which cools and often causes cloudiness and precipitation.
41Life Cycle of a Mid-latitude Cyclone Cyclogenesis: the birth of a mid-latitude cycloneOccurs only in the temperate zonesLargest weather system on the planet, ranging from 100 – 1500 miles in diameter
42A polar front separates the cold easterlies and the warmer westerlies. Phase 1A polar front separates the cold easterlies and the warmer westerlies.
43Phase 2A minor kink develops along the boundary. The cold air north of the front begins to push southward behind the cold front, and air behind the warm front advances northward.This creates a counterclockwise rotation around a weak developed low pressure system. Continued uplift leads to cloud formation.
45Phase 3A band of cumuliform cloud cover runs along and ahead of the cold front, caused by the displacement of the warm air by the cold denser air.Because of the high moisture content, intense rain, snow, and hail could occur.
47Phase 4The system becomes occluded and loses it warm, moist air fuel. The system begins to shut down.
48Cloud Formation Adiabatic Process: Parcel: A pocket of air which is heated by the earth’s surface by the process of conduction.Relative Humidity: The amount of water vapor in the air at a given temperature compared to the total amount of water vapor that the air could hold (saturation: 100%)Inverse relationship: As the temperature decreases, the relative humidity increases.
49Adiabatic Process cont. Normal Lapse Rate: Ambient air temperature will decrease at an average of 6.50 C per every 1000 m.Dry Adiabatic Lapse Rate: As the parcel of air rises the warmer air inside will decrease at a rate of 100 C per 1000 m.Wet Adiabatic Lapse Rate: When the parcel of air reaches 100% relative humidity, the lapse rate will decrease to 50 C per 1000 m
51Cloud Types There are four basic categories of clouds: Cirrus – Thin, wispy clouds made of ice crystalsStratus – Layered cloudsCumulus – Vertical developedNimbus – Rain producing clouds
52Classification of Clouds High clouds: cirrus, cirrostratus, and cirrocumulusMiddle clouds: altostratus and altocumulusLow clouds: stratus, stratocumulus andnimbostratusClouds with extreme vertical development: cumulus and cumulonimbus
58The are three stages in the formation of a thunderstorm: ThunderstormsThe are three stages in the formation of a thunderstorm:Stage 1: Cumulus StageStage 2: Mature StageStage 3: Dissipation Stage
59Cumulus Stage In the cumulus stage, an unstable parcel of air begins to rise due to by localized convection.The parcel of air cools adiabatically and creates the cumulus cloud.The atmosphere becomes humid enough that the newly formed cloud does not evaporate, but grows vertically.
64Dissipation StageIn the dissipation stage down drafts cut off the warm, moist air supply, that begins to shut down the entire system.
65Lightning Charge Separation: In order for lightning to be created there must first be a separation between positively and negatively charged atoms. Most often the positively charged particles accumulate in the upper portions of the cloud and the negatively charged particles in the lower portions with another layer of positively charged particles at the base of the cloud.
67Types of LightningFor lightning to occur, static electricity builds up within the cloud essentially becoming a massive battery.There are four main types of lightning:Internal cloud lightningCloud to air lightningCloud to cloud lightningCloud to ground lightning
68Internal Cloud Lightning Internal lightning occurs when a static charge is discharged within a cloud. This type of lightning is sometimes called “Heat Lightning”. However, heat lightning does not exist.
70Cloud to Cloud Lightning In cloud to cloud lightning, one cloud in the system discharges into a nearby cloud.80% of lightning is between cloudsCloud –to- cloud occurs when the voltage gradient within or between clouds overcomes the electrical resistance of the air.
72Cloud to GroundCloud to ground occurs the negatively charged particles accumulate in the base of the cloud and the positively charged particles that were at the base are forced to the ground.The negatively charged particles in the base of the cloud are repelled toward the ground forming a negatively charged column of ionized air called a “Stepped Leader”.
73Cloud to Ground cont.When the stepped leader reaches the ground and connects with the positively charged particles, the circuit is completed allowing the flow of electrons to occur. This known as the “return stroke”.The lightning bolt originates at the ground and travels back to the cloud.
74Cloud to Ground cont.The electrical charge of the average lightning bolt is approximately 20,000 amperes and reaches temperatures in excess of 30,0000 K or 54,0000 F or five times hotter than the surface of the sun.The amount of amperes required to stop a human heart is approximately .056 amps.
75Cloud to Ground cont.In a tenth of second following the main discharge, up to five smaller, sequential, discharges may occur that are called “dart leaders”. These discharges together happen so fast that the lightning appears to flash
79ThunderThunder occurs when superheated air from a lightning strike cools and produces a resonating tube surrounding the lightning's path. The nearby air rapidly expands and contracts. This causes the column to vibrate like a tubular drum head and produces a tremendous crack.The more forks off of the main bolt, the longer the rumble will be after the main crack.
80Supercell Thunderstorm A very large, single-cell thunderstorm with particularly strong up drafts. The updrafts of a super-cell rotates which could result in tornado development.Super-cell thunderstorms are responsible for the highest wind speed, most damaging hail, and the most destructive tornadoes.
83TornadoesTornadoes are the most violent of all the storms on Earth. Wind speeds can reach in excess of 300 mph.Tornadoes rotate cyclonically, (counter-clockwise) in the northern hemisphere 98% of the time.Tornadoes are zones of extremely rapid, rotating winds below a cumulonimbus cloud.
84Tornadoes cont.Strong tornadic winds form as a result of extremely large differences in atmospheric pressure over a short distance. Normally, the difference between a high and low pressure system is about 35 mb over thousands of kilometers. However, over just tenths of a kilometer the pressure difference from the core of the tornado and the outside air can be as great as 100 mb.
85Stage 1Fast moving air from the upper atmosphere opposes fast moving air in the lower atmosphere resulting in a rolling column of air between deep within the cloud called a mesocyclone.In order for a tornado to form, the mesocyclone must be at least approximately 6 miles in diameter.
87Stage 2Strong updrafts tilt the mesocyclone vertical. This produces the rotation of the clouds interior.The mesocyclone narrows and wind speeds increase. As the mesocyclone narrows and winds increase the base of the column rotating air becomes more dense and begins to descend from the base of the cloud creating a “wall cloud”.
93Tornado Watches and Warnings: Watch: A tornado watch is issued when weather conditions are favorable for tornadoes to form. These include heavy precipitation, high winds and large hail.Warning: A tornado warning is issued when a tornado has been observed on the ground and moving in a specific direction.
94Satellite image over Joplin Missouri May 25th 2011
95Doppler radar images of Joplin Missouri, May 22, 2011
99Hurricanes Hurricanes are the most powerful of all storms. The energy released by a single hurricane is more than the power consumption of the United States.Hurricane season in the northern hemisphere is from June 1st to November 30th.
100Names of HurricanesOver the Atlantic and Eastern Pacific oceans – HurricanesOver the Western Pacific Ocean – TyphoonsOver the Indian Ocean and Australia – Cyclones
101Stages of Hurricane Development There are four stages in the development of a hurricane. Stage 1: Tropical Disturbance Stage 2: Tropical Depression Stage 3: Tropical Storm Stage 4: Hurricane
102Stage 1Tropical Disturbance: A disorganized cluster of thunderstorms form in the southern Atlantic Ocean above 50 latitude. 90% of tropical disturbances do not develop further.
103Stage 2Tropical Depression: The pressure lowers causing the tropical disturbance to begin organizing in to bands of thunderstorms with cyclonic rotation. The system closes around a central point.
104Stage 3Tropical Storm: When wind speeds increase to 37 mph, the eye is named.
105Stage 4When the wind speed reaches 74 mph, and water temperature is above 790 F, the storm is classified as a Category 1 hurricane.
106The Eye Eye: A region of extreme low pressure, clear skies, descending air and light winds.The eye of a hurricane can range from 3.5 miles to 60 miles across.
107Eye Wall Eye Wall: The eye wall is the outer edge of the eye. This is the area of the most intense storm activity, strongest winds, thickest cloud cover, and most intense precipitation (100 in per day).
108Spiral Arms of a Hurricane Spiral bands of a hurricane are composed of numerous thunderstorms spinning counterclockwise around the eye.