1. Atmospheric Science

2. Air pollution kills more than 5
Air pollution kills more than 5.5 million people/year, the majority being in China & India
Feb 12, 2016 article; stat for indoor and outdoor air pollution; China/India account for 55% of deaths. China: burning coal, India: burning wood/biomass for cooking & heating

3. The Atmosphere

4. Layers of the Atmosphere Protects Earth’s surface from harmful X-ray &
UV radiation
Layers of the
Atmosphere
Ozone layer=
Pale blue gas O3
ABSORBS most of the Sun’s Ultraviolet-B & UV-C radiation
Provides critical protection because UV radiation is a mutagen & carcinogen
Mesosphere:
Coldest
Troposphere:
Weather occurs
in this zone

5. Atmospheric Properties
Air movement within the troposphere is caused by changes in …
Pressure & Density
Humidity
Temperature
1. Atmospheric Pressure & Density:
Gravity pulls gas molecules toward Earth’s surface and less so as altitude increases
That means the atmospheric pressure (the force per unit area produced by a column of air) decreases with altitude
With increasing height, you have more molecules below you than above you
Everests peak where air is “thin” you are 2/3 above the molecules in atmosphere
Airplane, you are 80% above molecules

6. Atmospheric Properties
2. Humidity
The ratio of water vapor a given volume of air contains
Phoenix, AZ 31% humidity vs tropical island of Guam, where it never goes below 80%
People are sensitive to changes in humidity because we perspire to cool our bodies
When humidity is high, the air is already holding nearly as much water vapor as it can, so sweat evaporates slowly and the body cannot cool itself efficiently

7. Atmospheric Properties
3. Temperature
Temperature varies over Earth’s surface because the sun’s rays strike some areas more directly than others.
On a local scale, temperature varies because of topography: plant cover vs asphalt (Heat Island Effect), proximity to water, etc.
Sunlight approaches poles at an angle, losing its intensity because its traveling longer distances through the atmosphere.

8. Heat Island Stable air mass that traps pollutants close to the ground
How they are created:
1. Asphalt & concrete-covered land absorb large amounts of heat that is re-radiated at night.
2. This heat retention creates an island of heat around a city that deflects weather would otherwise disperse pollutants.
3. As a result, pollutants are held close to the city
Temperatures in large cities can be up to 5 degrees higher than the surrounding areas.

9. Atmospheric Properties: Temperature
Energy from Sun heats air in atmosphere, which drives air movement, which helps create seasons and influences weather and climate (temperature & precipitation).
70% of solar energy from sun is absorbed by the atmosphere & Earth’s surface, the rest is reflected back.

10. Atmospheric Properties: Temperature
Due to tilt of the Earth on its axis, the Northern and Southern Hemispheres each tilt toward the sun for half the year, resulting in the change in seasons.
Regions near the equator are largely unaffected by this tilt (they experience 12 hours of sunlight 7 darkness everyday throughout the year)
Near the poles, however, the effect is strong and seasons are more pronounced.

11. Atmospheric Properties: Temperature
Convective circulation
Warm air is less dense, thus it will rise and create vertical atmospheric currents.
As the warm air rises into regions of lower atmospheric pressure, it expands and cools.
Once the air cools, it sinks and becomes denser, replacing warm air that is rising
The air picks up heat and moisture near ground level and prepares to rise again, continuing the process.
Similar convection patterns occur in ocean waters and in magma beneath Earth’s surface, or even in a pot of boiling water
Convective circulation influences both weather and climate

12. Convective Currents

14. “Climate is what we expect; weather is what we get.” –Mark Twain
Weather & climate involve physical properties of troposphere, like temperature, pressure, humidity, cloudiness and wind
Weather= atmospheric conditions over short periods of time (hours or days) within a geographic area
Climate= patterns of atmospheric conditions over a long period of time within a geographic area

15. Air masses interact to produce weather
Weather changes when air masses with different physical properties meet.
Boundary between air masses that differ in temperature and moisture= front
When a mass of warmer, moister air replaces a mass of colder, drier air= warm front
Produces a light rain
When a colder, drier air mass displaces a warmer, moister air mass= cold front
Produces thunderstorms

16. Air masses interact to produce weather
Air masses may also differ in atmospheric pressure.
High-pressure system= contains air that moves outward away from a center of high pressure as it descends
Brings fair weather
Low-pressure system= contains air that moves toward the low atmospheric pressure at the center of the system and spirals upward. The air will then expand and cool.
Brings clouds and precipitation

17. Temperature Inversions
Under most conditions, air in troposphere decreases in temperature as altitude increases.
Because warm air rises, vertical mixing occurs
Occasionally, however, a layer of cool air occurs beneath a layer of warmer air.
This is called a temperature inversion or thermal inversion
The cooler air is denser then the warmer air on top, so it resists vertical mixing & remains stable.
The effect: air pollutants are not dispersed but are “trapped” near the ground
Inversions regularly cause smog buildup in large cities
Commonly occurs in mountain valleys, where the slopes block morning sunlight, keeping ground-level air within the valley shaded and cooled

18. Temperature Inversions

19. Temperature Inversions

20. OTHER WEATHER PATTERNS THAT CAN OCCUR…
Grasshopper Effect
Aerosol Effect
TOXINS TEND TO BE TAKEN INTO THE ATMOSPHERE IN WARMER CLIMATES, AND RELEASED FROM THE ATMOSPHERE– often with precipitation– IN COOLER CLIMATES.
This results in a net transfer of pollutants from milder climates to cooler climates
Driven by 2 physical principles:
1. Convection cycles in atmosphere
2. Variable solubility of toxins in water at different temperatures
Particulate matter from forest fires, urban pollution & volcanoes cools the Earth

21. Circulation patterns produce climate
Convective air currents contribute to broad climatic patterns:
Near the equator, solar radiation sets in motion a pair of convective cells called Hadley cells.
The sun is most intense here, so the surface air warms, rises, and expands. As it does this, it releases moisture, producing the heavy rainfall attributed to tropical rainforests.
After releasing most of the moisture, the air diverges and moves in currents heading northward and southward
The air in these currents cools and descends back to Earth at about 30 degrees latitude north and south
These currents have low humidity, so the regions around 30 degrees latitude are quite arid, and give rise to deserts

23. Circulation patterns produce climate
There are two pairs of similar but less intense convective cells, called Ferrel cells and Polar cells
They lift air and create precipitation around 60 degrees latitude north and south and air to descend at around 30 degrees latitude in the polar regions
These three pairs of cells account for the distribution of moisture across Earth’s surface:
Wet climates near the equator
Dry/arid climates near 30 degrees latitude
Moist regions around 60 degrees latitude
Dry conditions near the poles
These patterns, along with temperature variation, explain the distribution of earth’s biomes

24. Wind patterns
The three pairs of cells interacting with the Earth’s rotation, produce global wind patterns:
As the Earth rotates on its axis, locations on the equator spin faster than locations near the poles
This causes the north-south air currents of the convective cells not to travel straight, but instead to deflect in a different direction.
This is known as the Coriolis Effect
Near the equator: doldrums, few winds
Between equator & 30 degrees: trade winds, blow from east to west
From 30 to 60 degrees: westerlies, blow west to east

25. Coriolis Effect

26. El Nino
This movement of wind, along with convective currents in ocean water create ocean current patterns.
Trade winds weaken periodically (thus affecting ocean currents), leading to El Nino conditions.

27. ocean currents & circulation
We will tie this information in to El Nino

28. Ocean currents
Ocean currents are driven by a combination of temperature, gravity, prevailing winds, the Coriolis Effect & the location of the continents
Northern Hemisphere: surface currents rotate in a clockwise direction
Southern Hemisphere: surface currents rotate in a counter-clockwise direction
These patterns of water circulation are called gyres
Gyres redistribute heat in the ocean, just as atmospheric convection currents redistribute heat in the atmosphere
California has cooler temperatures than areas at similar latitudes on the east coast because cold water from the polar regions moves along the west coasts of continents.
When you flush the toilet in the Northern Hemisphere, it rotates clockwise
When you flush it in the Southern Hemisphere…it goes in the opposite direction!

29. Great Pacific Garbage Patch
The Great Pacific garbage patch is a gyre of marine debris particles.
The patch has relatively high concentrations of pelagic plastics, chemical sludge and other debris that have been trapped by the currents of the North Pacific Gyre.
the Great Pacific garbage patch formed gradually as a result of ocean or marine pollution gathered by oceanic currents
The gyre's rotational pattern draws in waste material from across the North Pacific Ocean, including coastal waters off North America and Japan. As material is captured in the currents, wind-driven surface currents gradually move floating debris toward the center, trapping it in the region.

30. Warm water travels from lower to upper latitudes and vice versa
Surface currents
Driven by wind patterns
Deep currents
Caused by differences in density (salinity & temperature)
Denser, saltier water sinks and less-dense water rises
Colder water is more dense & sinks
90% of ocean volume circulates due to density differences in salinity & temperature. 10% is involved in wind-driven surface currents
Warm water travels from lower to upper latitudes and vice versa
Cold, salty (more dense) water sinks

31. Thermohaline Circulation
Therm= heat
Haline= salt
Thermohaline circulation drives the mixing of surface water & deep water and helps to mix the water of all the oceans
These ocean currents affect the temperature of nearby landmasses

32. Upwelling
Ocean currents help explain why some regions of the ocean support highly productive ecosystems
Along the west coasts of most continents, the surface currents separate from one another, causing deeper waters to rise & replace the water that has moved away.
This upward movement of water toward the surface is called upwelling
The deep waters bring w/them nutrients from the ocean bottom that supports large populations of producers
The producers, in turn, support large populations of fish that have long been important to commercial fisheries

33. El Nino-Southern Oscillation (ENSO)
Earth’s atmosphere & ocean interact in complex ways
Every 2-8 years, these interactions cause surface currents in the tropical Pacific Ocean to reverse direction
due to weak trade winds
These periodic changes in wind & ocean currents are collectively called El Nino-Southern Oscillation, or ENSO

34. El Nino-Southern Oscillation (ENSO)
Normal year:
During most years, trade winds push surface water from east to west
Deep water moves upward (upwelling) to replace surface water that has moved westward
El Nino year:
During El Nino years trade winds weaken or reverse direction; warm surface water moves from west to east
The warm surface water builds up along the coast of South America & prevents upwelling of the deep cold water

35. Normal year
El Nino year

36. Normal vs El Nino weather
Normal year
El Nino year

37. Impacts of ENSO
The weakening of the trade winds allows warm equatorial water to move towards the west coast of South America (instead of east-ward)
This suppresses upwelling off the coast of Peru. Because the nutrients aren’t coming upwards, it decreases productivity & reduces the fish population near the coast.
It is called El Nino because it often begins around Dec. 25th

38. Impacts of ENSO Globally
El Nino events alter weather patterns around the world:
Creates rainstorms & floods in areas that are usually dry (like southern California)
Causes drought & fire in regions that are typically moist (like Indonesia)
El Nino brings warmer sea
temperatures
El Nino can last from a few
weeks to a few years

39. La Nina These events are the opposite of El Nino events.
Cold surface waters extend far westward in the equatorial Pacific, and weather patterns are affected in opposite ways of El Nino

40. El Nino and La Nina Overview
El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short.
The pattern can shift back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature, precipitation, and winds.
These changes disrupt the large-scale air movements in the tropics, triggering a cascade of global side effects.