GG101 Lectures 5-11

Atmosphere

• the gaseous envelope that surrounds the earth

  • mixture of gasses and suspended liquids and solids

Aerosols

• liquids and solids (but not water or ice) that are suspended in the atmosphere

What happens with mass as we increase heigh (altitude) in the atmosphere?

• as we move upward, the density decreases

Troposphere

• first layer

• 0 to 17-18 km (equatorial)

• 0 to 8-10 km (polar)

• 80% if the mass of the atmospehre

• lowest layer of the earths atmosphere

• tropopause

Stratosphere

• second layer

• 15 to 50 km above the earths surface

• temperature increases due to UV particles form the ozone layer

• limited circulation between the troposphere and stratosphere

• directly above the Troposphere

• stratopause

Mesosphere

• third layer

• above the stratosphere

• 50-85km above the earths surface

• low air pressure and low temperature, with temperature decreasing altitude

Thermosphere

• 4th layer

• above the mesosphere

• 85km to several hundred kms above the earths surface

• low air density and high temperatures

Energy balance

• Refers to the equilibrium between the incoming energy from various sources and the outgoing energy that is emitted or reflected back into space within a given system

Radiation and Matter interactions

• when electromagnetic radiation comes into contact with matter, there are several possible outcomes

  • transmission

  • refraction

  • reflection

  • scattering

  • absorption

Albedo

• albedo is the proportion of K down that is reflected or scattered from the surface and/or atmosphere

  • ○      Albedo = (K↑/ K↓)×100 = % value

Heat

• energy in the process of being transferred from one object to another due to the temperature difference between them

Sensible Heat

• heat that we can feel and measure with a thermometer

Latent Heat

• heat required to activate a phase change from one state to another with no temperature change

Heat Transfers are accomplished by:

• conduction

• convection

• radiation

What happens to shortwave radiation absorbed at the surface?

• re-radiated as long wave, infrared radiation, also known as heat

  • transferred to the atmosphere as

    • latent heat

    • sensible heat

    • emitted long wave radiation

what haeppsn when that energy is absorbed in the atmosphere?

• the atmosphere emits long wave radiation, much directed towards the surface L down

• the long wave radiation is absorbed at the surface and the process repeats

• causes:

  • burning, fossil fuels, cutting down forests and farming livestock

• effects/consequences

  • global warming and climate change

What happens on clear vs cloudy nights

• On cloudy nights, the radiations from earth's surface reaching cloud are reflected back so the temperature of earth does not fall (doesn't get colder)

• On clear nights, earth’s surface escapes out so, earth’s temperature falls (gets colder)

major regional controls on temperature

• latitude

• differential heating of land and water

• altitude

• ocean currents

• cloud cover

latitude

• dominant control

• influences the receipt of solar radiation

• pattern: warmest equatorial region, coolest in polar region

Specific Heat

• amount of heat required to raise 1 gram of a substance by 1 degree c at sea level atmospheric pressure

• water

  • 4.2 joules

• land

  • 0.8-0.9 joules

differential heating of land and water

• thermal differences between land and water

  • specific heat

  • surface:

    • transparent

    • opaque

    • evaporation

    • convection

    • thermal storage

Continental climate

• not influenced by the moderating effect of large water bodies

marine (maritime) climate

• moderated by proximity to a large water body

continentality

• a measure of the difference between continental and marine climates characterized by the increased range of temperatures that occur over land compares with water

altitude (elevation)

• pressure, density and temperature decrease with altitude

ocean currents

• proximity to ocean currents can influence the temperatures of adjacent land areas

  • example: Gulf Stream

Cloud Cover

• type, height and density of cloud influences temperature through controls on albedo and long wave radiation

• clouds moderate temperature

●      Which of the following best describes the main methodology governing geographic inquiry?

a.     Spatial analysis

b.     Behavioral analysis

c.     Chronological organization

d.     Reasoning systematics

Spatial analysis

What is the primary cause of the uneven distribution of insolation by latitude?

• The curvature of earth (tilted on its axis and orbits the sun, different latitudes receive varying amounts of sunlight at different times of the year)

Why these patterns in air movement (wind)

• air moves (wind) in response to variations in

  • air pressure

  • measure air pressure with a barometer

Pressure from gradient force

• drives air from high air pressure to low pressure

• crosses isobar at right angles

• stronger where the pressure gradient is steep

Coriolis force

• consider an object in motion on a rotating reference frame

Coriolis force produces the Coriolis effect

• effect is the apparent deflection of the wind from a straight oath (when viewed from the surface) due to the rotation of earth

Coriolis Effect

• Coriolis deflects wind to the right in the northern hemisphere and to the left in the southern hemisphere

geostrophic and Gradient Winds

• wind pattern development

  • upper atmosphere

  • geostrophic winds and gradients winds

Friction Force

• friction acts on wind when the air approaches the surface

  • slows the wind speed by exerting drag

What is the effect of friction on the geostrophic wind (gradient wind)

• produces surface winds

High pressure area

• anticyclones

Low pressure

• cyclones

High and Low pressure areas

• develop in response to air flow in the upper troposphere and uneven heating of the lower atmosphere

Humidity

• refers to the water vapour content of the atmosphere

• an understanding of humidity is needed in the study of stability, clouds, fog and precipitation

Specific Humidity (Q)

• Mass of water vapour in grams per kg of air

Absolute Humidity

• mass of water vapour in grams per grams per cubic meter of air

Mixing ratio

• mass of water vapour in kg, per kg mass of dry air

Vapor pressure (e)

• partial pressure of water vapour

Relative Humidity

• water vapour content of the air, relative to its maximum vapour content, expressed as a percentage

Stability

• refers to the tendency of a parcel of air to rise in the atmosphere

Adiabatic Processes

• consider a parcel of air (of a given temperature and humidity) rising or falling in the atmosphere

• temperature changes because of compression or expansion (without gain or loss of heat surrounding air)

ELR (Environmental Lapse Rate)

• rate at which air temperature changes with height in the atmosphere

• normal lapse rate 6.4 degrees celsius

DALR (dry adiabatic lapse rate)

• rate at which a dry (unsaturated) parcel of air cools or warms with height

• 10 degrees celsius

Lifting Condesnation Level (LCL)

• The level at which an air parcel becomes saturated (100% rh)

• water droplets are condensing, release sensible heat

• cloud formation

Clouds

• a visible aggregate of water droplets and ice crystals that are suspended in the air

Fog

• cloud at ground level

• formed due to air temperature dropping to the dew point

Advection Fog

• warm moist air moving over older land

Radiation Fog

• Clear nights, lots of heat escapes the cold ground, reaches Td

Evaporation fog (aka sea smoke)

• water evaporating into colder air above

Air Masses

• a large body of air with relatively uniform temperature and moisture characteristics

Source Region

• area where air masses remain relatively stationary for some days

Fronts

• boundary or contact between air masses

Cold front

• cold air mass moves into warmer air asses

Warm front

• warm air mass moves into colder air mass

Cyclone

• an enclosed area of low pressure with air circulation in a spiral or vertex

Wave cyclone

• system of the mid and high latitudes, a moving vortex with warm and cold air masses