chapter 4 weather. solar radiation temperature changes with latitude like equator like at poles
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The Atmosphere• Nitrogen 78%
• Oxygen 21%
• CO2 .038%
Carbon dioxideArgonWater vaporPollutantsHeliumEtc.
1%
Atmospheric Circulation
• Atmospheric Circulation
Circulation spawned by heating / cooling
Prevailing winds:
Generated by pressure differences and Coriolis effect
Horse Latitudes
30 degrees north(Horse latitudes)
&30 degrees south(Horse Latitudes)
&Equator(Doldrums)
• Size of deflection is directly related to both the speed at which the air is moving and its latitude.
• The Coriolis force is zero right at the equator.
• The Coriolis force only acts on large objects like air masses moving considerable distances. Small objects, for example ships at sea, are too small to experience significant deflections.
Gaspard de Coriolis (1792-1843)
El Niño/Southern Oscillation (ENSO)
• Chicken and Egg scenario – ocean temperatures or trade winds?
This decreases during El Niño
Increases during La Niña
http://esminfo.prenhall.com/science/geoanimations/animations/26_NinoNina.html
El Niño/Southern Oscillation (ENSO) – enso only refers to el nino
1. Heavier rainfall over coastal equatorial South America
2. Drought in Western Pacific (Indonesia & Australia)
3. Increased transmission of disease – mosquitoes and stagnant water – Les or More water and heat
4. Migration of fish species (North or South – Inshore or Out)
5. Death of seals and sea birds due to changing fisheries
6. Heavier rains in the southwestern deserts of United States
7. Fewer hurricanes in the Atlantic
8. Changes in disease due to shifts in temperature and moisture
2010-2011 Australia has record flooding?• La Nina or El Nino• Weak or Strong
Tornados
• Tornado formation: http://www.youtube.com/watch?v=7KDz6dGQ5RE
• Tornado Formation: http://www.youtube.com/watch?v=MjjwPQRVbWk
• Tornado Formation http://www.youtube.com/watch?v=7bHSS1ImFQI
The Global Ocean• Patterns of Circulation in the Ocean
Influenced by:
1. Coriolis Effect 2. Winds
3. Land Masses 4. Water Density
1. Anatomy of a Hurricanehttp://www.youtube.com/watch?v=HJydFJORWf4&feature=related
2. Hurricane Formation: http://www.youtube.com/watch?v=SNEG4YKElgY
Hurricanes• Severe weather events:• Tropical cyclones• Atlantic Ocean = hurricanes• Pacific Ocean = typhoons• Indian Ocean = cyclones
Category One Hurricane: Winds 74-95 mph Category Two Hurricane: Winds 96-110 mph - Storm surge generally 6-8 feet above normalCategory Three Hurricane: Winds 111-130 mph - Some structural damage to small residencesCategory Four Hurricane: Winds 131-155 mph - Complete destruction of mobile homesCategory Five Hurricane: Winds greater than 155 mph - Storm surge generally greater than 18 ft above normal and framed homes destroyed
Hurricanes1. Hurricanes are powered by the energy released during condensation
2. Hurricanes are steered by prevailing wind patterns and wind sheer will destroy a hurricane.
3. What are positive and what are negative feed-back-loops for hurricanes
4. When winds reach 74mph a tropical storm becomes a hurricane
5. Why is the eye clear? Air coming in from the eye wall is coming inward towards the center from all directions. This convergence causes the air to sink in the eye. This sinking creates a warmer environment and the clouds evaporate leaving a clear area in the center.
1. A front is defined by temperature, relative humidity, and air pressure:1. Temperature = the kinetic energy of a substance2. Relative Humidity = is a function of temperature and water content3. Air pressure = the weight of the atmosphere
Warm Fronts1. Retreating Cold fronts under advancing warm fronts are drawn out in a triangular fashion due to friction with the ground causing a triangular shape to the advancing warm front. 2. Warm fronts move towards the northeast3. Warm fronts usually travel at about 15mph
Cold Fronts1. Cold fronts become rounded due to friction with the ground as they advance on warm fronts.2. Cold fronts tend to move towards the east or southeast3. Cold fronts usually advance at speeds of 20mph4. Cold fronts may produce violent weather depending on their speed and air stability. 5. Faster moving cold fronts produce “squall Lines” Where high upper level winds stop a warm front from lifting up but whip up warm air ahead of the storm producing violent weather.
Fronts
Pressure Systems (in the north)1. Low Pressure systems rotate counter clockwise2. High pressure systems rotate clockwise
Jet Streams1. Tend to follow the borders between warm and cold air2. In the summer they are located further north and in the winter further south3. Jet streams blow west to east in the northern and southern hemispheres4. How are airline flights impacted by jet streams (speed and turbulence)
Wind Shear1.Is any sudden change in wind speed or direction causing, turbulence.
Air Movement
Katabatic WindsKatabatic winds exist in many parts of the World and are winds that flow from the high elevations of mountains, plateaus, and hills down their slopes to the valleys or planes below. There are many diffent names for katabatic winds depending where they are located - Santa Anna (funneled & dry), and Chinook (dry).
1. A 10k foot mountain2. Air temperature at mountains base is 60 degrees3. Clouds form at 4k and extend to the mountain top4. What is the temperature of the valley floor (leeward side)5. How does humidity and temperature change from winward to leeward?
Problem 2A 14k peak with a valley temperature of 70Cloud formation begins at 7k and ends at 10k(5.5 and 3.2 = temperature changes for every thousand feet)
1. What is the temperature at 7K?2. What is the temperature at 10K?3. What is the temperature at 14K?4. What is the temperature in the leeward valley?
Is there compression of the air as in refrigeration or a decompression?
Adiabatic Problems
Adiabatic heating and cooling is a temperature change within a gas due to compression (resulting in heating) and expansion (resulting in cooling); no heat is added to, or removed from the gas.
Why rising air cools and Rain Shadows
1. Decreased pressure
2. For every 1k/feet air rises it cools 5.5 farenheight due to lowering gas pressures and heats the same going down (adiabatic cooling & heating)
3. Air that rises and condenses at the same time only cools 3.2F for every 1k it rises due to the “heat of condensation”
4. Air moving up western slopes can come down warmer on the other side. Creating cool moist western slopes and warm dry eastern slopes.
Adiabatic Temperature Change & Condensation
Lightning
What do you know about lightning
1. Lightning 5 min. – http://www.youtube.com/watch?v=Q3Awp-3CxSU
2. http://www.youtube.com/watch?v=6MUYsIjTKvk
Lightning
Thunder and Lightning
1. Sound travels about one mile every 5 secondsSo if you count to ten the storm is 2 miles away
2. Thunder rumbles because the sound from different points on the bolt reaches our ears at different times
3. Thunder, is produced by the heating (expansion) and cooling (contraction) of the air around a lightning strike.
4. Lightning forms from negative charges at the bottom of the cloud that meet with positive charges from the ground. A stepped leader from the cloud meets a streamer from the ground. Visible light moves up and charge flows down. Individual charges are drained separately causing lightening to flash and strike multiple times in one location.
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