The Atmosphere
▪ Weather
▪ Climate
▪ Climatology
▪ Atmosphere
▸ Composition
▸ Structure
Layers of the Atmosphere
1
Temperature
▪ INcoming SOLar radiATION (insolation)
▸ reflection
▸ absorption
▪ Albedo
Global Energy Balance Equation
–Q* is the net all-wave radiation
– K* is the balance between the net shortwave radiation and net
longwave radiation (L*).
–net radiation input is balanced by three heat fluxes:
–sensible heat flux (QH) +/- due to change in temperature
–latent heat flux (QE) +/- due to change of state (i.e. liquid to gas)
–subsurface heat flux (QG) +/- from surface to subsurface of earth
–The equation is solved by searching a unique equilibrium
surface temperature that results in a balance.
2
Temperature
▪ isotherms
3
World Temperatures
World Temperatures, Oct. 4, 2010
4
Influences on Temperature:
Angle of
Sunlight
(Latitude)
Influences on Temperature
▪ Tilt of Earth
▪ http://www.physicalgeography.net/fundamentals/7v.html
5
▪ Water in Atmosphere
Greenhouse Effect
6
Other Influences -- Elevation
elevation can profoundly affect climate
Other influences -- Surface
Albedo - index of reflection of solar energy
−
High (reflection) -- ice, desert, farm land
−
Low (absorption) -- oceans, tropics, forests
−
Shape of Land
−
Mountains as barriers
−
Elevation
7
Other influences -- Pressure/Winds
▪ Air pressure/Winds
Hadley cells
• move air in lower and
upper atmosphere as it
heats and cools
• deflected by rotation of
earth to produce winds
Ocean Currents
Heat exchange from water to air
8
Precipitation
▪ Influences
▸ availability of water (humidity)
▸ air pressure (rising/falling)
▸ movement of air (winds)
▸ shape of land (topography)
Orographic Precipitation
▪ warm moist air forced by shape of land to rise
▸ i.e. Vancouver
▸ Rainshadow – Cool dry air descends on leeward side of mountain
9
Convectional Precipitation
▪ sunlight heats earth’s surface, warms air above
it like the heating element in an oven
–example – tropics, Canadian prairies in summer
Frontal Precipitation
▪ when cold and warm air masses collide
▸ example – Montreal
10
World Precipitation – May to October
Source: www.maps101.com
11
World Precipitation – November to April
Source: www.maps101.com
Climographs
▸graph of climate data
– 40 year average
▸x-axis
– months
▸left y-axis
– average monthly
temperature (°C)
– graphed as line
▸right y-axis
– average monthly
precipitation (cm)
– graphed as bars
12
Classifying Climates
Koppen Climate Classification System:
▪Five main climate types
• defined by temperature and precipitation
• A Tropical
• B Dry Subtropical
• C Mild Mid Latitudes
• D Continental Mid Latitudes
• E Polar
▪Sixth type added by Trewartha -- H Highland (highly variable)
World Climates
13
Koppen Climate Classification System (con’t)
▪ can add 2-3 lower case letters giving more detailed
information about temperature or precipitation
•
a -- Warmest Month >22̊C
•
b -- Warmest Month <22̊C
•
c -- Less than 4 months >10̊C
•
d -- Less than 4 months >10̊C and coldest month <-38̊C
•
f – Constantly moist (precipitation all year)
•
s -- Dry season in summer (<30% of annual precipitation)
•
w -- Dry season in winter (<30% of annual precipitation)
•
etc.
▪ classifying a place is a process of steps (see Workbook)
14
As
Tropical Climates (A)
▪ Around Equator
▪ Average temperatures
never below 18°C
▪ Rainfall can be constant
(Tropical rainforests) or
seasonal (Savannah or
monsoon)
15
Tropical Climates
Am
Af
Aw
16
Dry Climates (B)
▪ Obviously defined
mainly by precipitation
▪ Can be:
• hot (BW) deserts
• cold (BS) steppe
Dry Climates
17
BS
BW
Mild Climates (C)
▪ Mostly on seacoasts
▪ Average temperature
never falls below freezing
▪ Rainfall can be
• constant (f)
• seasonal (s) or (w)
18
Mild Climates
Cbs
Ca
Ccf
19
Midlatitude Continental Climates (D)
▪ Only in northern
hemisphere
▪ Warm summers
(>10°C) and cold
winters (<0°C)
▪ Rainfall can vary by
season, but most are
moist year- round
Db
Da
Dc
20
Midlatitude Continental Climate
Cold Climates (E)
▪ Located near poles
▪ Average temperatures
never > 10°C
• Tundra climates
(ET) > 0°C in
summer
• Perpetual frost (EF)
(ice cap) climates <
0°C in summer
21
EF
ET
22
Highland Climates (H)
23