- The state of the atmosphere at a given time in a particular place.
- The three main factors of weather are humidity, air pressure, and temperature.
- the average weather conditions at a particular place over a long period of time. Climate is the long-term predictable state of the atmosphere.
- It is affected by physical features such as mountains, rivers, positioning of the globe, plateaus, deserts, depressions and much more.
- The climate of a place is given names such as Temperate, Arid, Cold, Dry, Tundra, Tropical, Equatorial, Mediterranean,
- the lower 10 km of the Earth’s atmosphere. Where most “weather” takes place.
- concerned with the special arraignment of climate over the face of the earth and the processes which contribute to the distribution.
- a measure of the heat content of the air - controlled by a complex set of interactions between the biosphere, lithosphere and atmosphere
· Intensity of insolation – determined by the angle of the earth
· Duration of insolation – determined by the hours of daylight
· Amount of water vapor in the air
· Degree of cloud cover
· Nature of the biosphere (landsurface)
· Elevation of sea level
· Degree and direction of air movement
- The Earth is tilted approximately 23.5° from the perpendicular
- This is a variable and the actual tilt has varied from around 22° to 24.5°It is believed that variations in the tilt affect ice ages
- Due to the tilt the vertical rays of the sun strike the Earth at different places as the earth rotates around it and thus the highest intensity varies.
- Vertical strike = highest energy exchange
- When the Northern Hemisphere is tilted directly toward the sun the vertical rays strike at approximately 23.5° N latitude (Tropic of Cancer).
- Occurs about 21 June, the Summer Solstice for the Northern Hemisphere
- When the vertical rays strike approximately 23.5° S latitude (Tropic of Capricorn) this is the Winter Solstice in the Northern Hemisphere.
- The Spring and Fall Equinoxes occur when the vertical strike is on the Equator.
- 12 hours at the Equator and then variable to the north and south
- Length of daylight away from the Equator depends on where the vertical strike happens.
- Most effect from the changing vertical strike occurs between 15° and 30° north and south latitude (affected by the strike angle of the sun’s rays).
- Reflection
- When insolation is sent back out into space or diffused within the troposphere.
- Clouds and light colored surfaces increase the rate of reflection
- Reradiation
- The return of terrestrial energy to the atmosphere in the form of terrestrial radiation.
- Cloud cover
- Water or land
- Ground Cover
- Water more efficiently absorbs and distributes solar heat
- Marine environments – land areas affected by the moderating influence of nearby water
- Continental environments – those areas not affected by the moderating influence of water
- Lapse Rate – Elevation
- Temperatures closest to the earth’s surface are warmer than those higher in the atmosphere
- Approximately 6.4°C for every 1000 meters
- Temperature Inversion
- When the colder air is closer to the land surface and the warmer are is above it.
- The weight of the air at a specific point in the air column. Generally targeted for the pressure at ground or sea level.
- Cold air is heavier than warm air (temperature Inversion)
- This creates the high and low pressure areas
- Measured using a Barometer
- Wind flows from high to low pressure areas
- Wind speed is affected by the strength of the high and low pressure areas and the distance between them.
- Convection System
- when surface heated air rises and is replaced by cool air from above
- Land and Sea breezes
- caused by the day/night temperature differential between water and land
- inland daytime breeze as warm air over land rises
- nighttime sea breeze as warm air over the water rises
- Mountain and Valley Breezes
- gravitational forces bring cool air from upslope into the valleys – creating a temperature inversion, usually happen during the night
- warm air moves upslope during the day as the valleys are warmed
- The Coriolis Effect
- The sheer or change of direction of wind due to the rotation and shape of the earth
- In general, the effect deflects objects moving along the surface of the Earth to the right of the direction of travel in the Northern hemisphere and to the left of the direction of travel in the Southern hemisphere.
- As a consequence, winds around the center of a cyclone rotate counterclockwise on the northern hemisphere and clockwise on the southern hemisphere
- The Frictional Effect
- The effect that the landsurface has on wind, a slowing and directional modification dependent upon the topography and ground cover.
- Disappears about 1,500 meters above the landsurface
- Driven by Equatorial Zones of Low Pressure due to higher heat in those regions.
- Subtropical High Pressure areas located approximately 30° N and S of the equator due to falling colder air.
- Belts of Wind – Northern Hemisphere (names generally refer to the direction from which the winds come)
- Northeast Trades – in the tropics
- Westerlies – in the mid-latitudes
- Subpolar Lows
- Polar Easterlies
- Polar High
- Jet Streams
- strong flows of upper atmosphere winds, from west to east in both hemispheres
- Monsoon Winds
- winds which change direction seasonally
- Surface currents mimic wind patterns as wind creates these currents
- Deeper currents affected by water density
- Water below High Pressure systems is denser due to increased evaporation and higher percentages of minerals.
- Shape of ocean basin affects currents.
- Pacific Current moving east to west splits and moves north and south when it hits the North American continent
- Atlantic Current is pushed north and east
- Creates the North Atlantic Drift – bringing warm water to
- Cold water reduces precipitation while warm water increases precipitation
- Precipitation – any form of water that falls from the atmosphere
- supersaturated – when water vapor condenses and forms droplets
- condensation nuclei – particles around which vapor condenses
- Clouds
- clouds form when condensed water vapor remains light enough to be supported by air currents
- Cumulo-nimbus: formed by rising warm, moist air
- Stratus: low, gray more common in cooler seasons
- Cirrus: high, wispy and made entirely of ice crystals
- Relative Humidity
- a percentage measure of the moisture in the air
- varies with temperature
- Convectional Precipitation
- from rising heated, moisture-laden air
- summer, tropical, and continental regions and seasons
- afternoon and early evening
- may produce hail
- Orographic Precipitation
- warm, moist air is forced to rise due to hills or mountains
- when mountains or hills are downwind of large bodies of water
- Windward Side – where the wind brings in the moisture
- Leeward Side – rain shadow with little precipitation
- Cyclonic or Frontal Precipitation
- where cool and warm air masses meet
- common in the mid-latitudes
- also originates hurricanes and typhoons
- form over a Source Region
- large areas of uniform surface and relatively consistent temperatures
- when the air mass begins to move it forms a Front
- Storms
- form at the frontal boundary of air masses
- El Niño
- forms off the western coast of Central and
- winds blow from east to west
- blow across the
Soil
- a layer of fine material containing organic and inorganic matter which rests on the bedrock under-lying it.
- Soil Formation
- Geologic Factor: underlying bedrock
- Climatic Factor: temperature and precipitation
- Topographic Factor: land elevation
- Slope Aspect – direction it faces
- Slope Angle – how steep
- Biological Factor: living and dead organisms
- Chronological Factor: how long the previous factors have been working
- Soil Profiles and Horizons
- Horizon: strata within the soil
- Profile: a vertical cross-section of the soil
- O-Horizon: the surface strata, formed mainly of organic material
- A-Horizon: topsoil, fertile, mineral-based material. Large amounts of organic material and biological activity. Generally a dark color.
- E-Horizon: Eluviation – the washing out of organic and mineral material from the A-Horizon – a lighter colored soil below the A-H
- B-Horizon: Zone of Illuviation (in-washing) – less fertile due to reduced organic load – color depends on mineral content
- C-Horizon: decaying bedrock, zone of weathering
- R-Horizon: (Regolith) – the unaltered bedrock – generally used only if this zone is within two meters of the surface
- Soil Properties
- Texture – size of the mineral matter in the soil – determined by the proportion of sand, silt and clay particles
- Loam is the most productive soil
- Structure – how the individual soil particles clump
- Nutrients – how rich or poor the soil is
- Color – what is the color of the soil
- Acidity or Alkalinity – what is the Ph of the soil
- Soil Taxonomy (developed by the US Dept of Agriculture) – divides soil into 12 orders which are then subdivided into suborders, great groups, subgroups, families, and series.
- Soil Order
- a very general grouping of soils with similar compositions, horizons, weathering, and leaching processes.
- The vegetation which would exist in an area if it were not modified by humans
- Succession – the development of the natural vegetation – reaches a final stage of equilibrium
- Pioneer plant community (lichens and mosses)
- Grasses and weeds
- Mixed Herbaceous
- Shrubs
- Mature
- Tundra
- Coniferous Forests
- Deciduous Forests
- Prairie or Steppe
- Desert
- Semi-desert
- Savanna
- Generally found between the Tropics of Cancer and Capricorn
- Generally warm and wet throughout the year
- Poor agricultural soils
- Tropical Rain Forests
- Savanna
- Monsoon
- Generally in the interior of continents
- In the rain shadow of mountains
- Hot and Cold Deserts
- Steppes
- Semi-deserts
- Warm summers and cool winters
- Generally in the western portions of continents in the Midlatitudes
- Between the Subtropical Highs and the Moist Westerly Zones
- Seasonal (winter) Rainfall
- Warm, dry summers; mild, wet winters
- Generally on the eastern portions of continents
- Hot, moist summers; moderate, moist winters
- Deciduous forests
- Within the westerly wind belt
- Moderate, wet summers; Cool, wet winters
- Cyclonic storms
- Cool summers; cold winters
- Coniferous forests to steppes
- Short, cool summers; long, cold winters
- Limited snowfall
- Tundra
- High elevations
- More similar to colder climates
- Affected by location and facing
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