Ecology exam 1: lecture 2

Milankovitch Cycles and Long-Term Climate Variation

The angle of axis tilt changes in cycles of about 41,000 years.

Weather

current conditions - temp., precipitation, humidity, cloud cover.

Climate

Long-term description of weather, based on averages and variation measured over decades; includes daily and seasonal cycles, as well as yearly and decadal cycles

Intertropical Convergense Zone (ITCZ)

Seasonal changes in precipitation result from movement of the ITCZ, the zone of the max solar radiation and atmospheric uplift.

Conduction

kinetic energy is transferred by molecules in direct contact with one another

Convention

Energy transfer by movements of air or water currents

latent heat flux

energy transfer from warm air immediately above the surface to the cooler atmosphere by convection and conduction

sensible heat flux

energy transfer from warm air immediately above the surface to the cooler atmosphere by convection and conduction

Albedo

amount of solar radiation a surface reflects

→ light colored surfaces have the highest albedo

→ A coniferous forest has a darker color and lower albedo than bare soil or dormant grassland and absorbs more solar energy

Evapotranspiration

Water loss through transpiration by plants, plus evaporation from the soil. The transfer of energy as latent heat and water into the atmosphere, impacts air temp and moisture

What does decreased evapotranspiration result in?

Less moisture in the atmosphere and less precipitation

→ Deforestation in the tropics can lead to a warmer, drier regional climate

Atomospheric pressure

decreases with altitude, so the rising air expands and cools. Condensation is a warming process, so the pocket of air stays warmer than the surrounding atmosphere and enhances its uplift.

Subsidence

air descends when it cools and forms a high-pressure zone (major deserts of the world are at these latitudes)

Hadley cells

Large scale circulation patterns from uplift in the tropics

Polar cells

at the north and south poles - cole air descends, creating high pressure zones with little precipitation (polar deserts)

Ferrell Cells

exist at mid-latitudes. These atmospheric circulation cells result in the major climatic zones in each hemisphere - tropical, temperate, and polar zones

Prevailing winds

winds flow from areas of high pressure to areas of low pressure, resulting in consistent patterns of air movements

The Coriolis effect

The winds appear to be deflected due to the rotation of the Earth

What influences regional climate

ocean currents

Water has a higher ____ heat capacity than land - it can absorb and store more energy without changing temp

heat capacity

Semipermanent high and low pressure cells

Seasonal shifts in pressure cells influence the direction of the prevailing winds

What do coastal areas have? and what are they?

maritime climate - little daily and seasonal variation in temp and high humidity

What do areas in the center of large continents have? and what are they?

continental climates - much greater variation in daily and seasonal temps, especially in temp zones

Make a list of abiotic factors impacting ecosystems (1)

1. weather

   1. precipitation (water availability)

   2. temp,

   3. humidity,

   4. seasonality

   5. wind (air)

   6. sunlight availability

Make a list of abiotic factors impacting ecosystems (2)

2. terrestrial: soil composition

Make a list of abiotic factors impacting ecosystems (3)

3. Water composition

   1. salinity

   2. nutrient availablilty

   3. oxygen levels