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2.4.1 Climate describes atmospheric conditions over relatively long periods of time, whereas weather describes the conditions in the atmosphere over a short period of time.
Weather refers to the specific conditions being experienced at a particular time or over a short period, including temperature, humidity, air pressure and wind speed. Climate is the average of these conditions over approximately 30 years
2.4.2 A biome is a group of comparable ecosystems that have developed in similar climatic conditions, wherever they occur.
Ecosystems developed in similar conditions in different parts of the world can have many parallel features.
Precipitation, temperature and insolation are major influences on the distribution of terrestrial biomes.
Ecosystems found in Hokkaido have parallels elsewhere (so the pairs of ecosystem are part of the same biome).
Hokkaido
Hokkaido
Hokkaido
Vermont
Tierra del Fuego
Sweden
Different tropical rainforests contain species that are different but functionally similar (e.g different species of monkeys).
Costa Rica
DR Congo
Sumatra
2.4.3 Abiotic factors are the determinants of terrestrial biome distribution.
For any given temperature and rainfall pattern, one natural ecosystem type is likely to develop. Consider a graph showing the distribution of biomes with temperature and rainfall pattern on the horizontal and vertical axes.
Analyse and discuss in pairs: do the models below match up to the model above? For example, does the total annual precipitation (note that below shows mm and above shows cm, so divide by 10 to convert) and average temperature (guesstimate the latter) in TRF shown below match with the levels above?
Sapporo and London are large cities. Use the models below to predict the vegetation type in the areas before the cities were established.
2.4.4 Biomes can be categorized into groups that include freshwater, marine, forest, grassland, desert and tundra. Each of these groups has characteristic abiotic limiting factors, productivity and diversity. They may be further classed into many subcategories (for example, temperate forests, tropical rainforests and boreal forests).
Watch the video and make notes.
Copy and complete the table. The slides towards the end above and the biome viewer could help.
Include the characteristic limiting factors, productivity and resulting biodiversity of tropical rainforests, hot deserts, tundra and at least two other biomes.
2.4.5 The tricellular model of atmospheric circulation explains the behaviour of atmospheric systems and the distribution of precipitation and temperature at different latitudes. It also explains how these factors influence the structure and relative productivity of different terrestrial biomes.
Latitude is the angular distance from the equator (north or south of it) as measured from the centre of the Earth (usually in degrees). Give details of the tricellular model with the three distinct cells: the Hadley cell, the Ferrel cell and the polar cell. Include reasons for the distribution of biomes using the tricellular model.
Watch the video and make notes.
2.4.6 The oceans absorb solar radiation and ocean currents distribute the resulting heat around the world.
Watch the video and make notes.
Details of the great ocean conveyor belt and thermohaline circulation are HL only.
2.4.7 Global warming is leading to changing climates and shifts in biomes.
The general trend is of biomes moving poleward and to higher altitude.
Read the articles below.
Biomes.pdfHL ONLY CONTENT
HL ONLY CONTENT
2.4.8 There are three general patterns of climate types that are connected to biome types.
2.4.9 The biome predicted by any given temperature and rainfall pattern may not develop in an area because of secondary influences or human interventions.
How much the following affect biome distribution
Soil
Topography
Fire
Urbanisation
2.4.10 The El Niño Southern Oscillation (ENSO) cycle is the fluctuation in wind and sea surface temperatures that characterizes conditions in the tropical Pacific Ocean. The two opposite and extreme states are El Niño and La Niña, with transitional and neutral states between the extremes.
2.4.8 There are three general patterns of climate types that are connected to biome types.
2.4.11 El Niño is due to a weakening or reversal of the normal east–west (Walker) circulation, which increases surface stratification and decreases upwelling of cold, nutrient-rich water near the coast of north-western South America. La Niña is due to a strengthening of the Walker circulation and reversal of other effects of El Niño.
Consider how El Niño and La Niña events develop and also consider that the ENSO cycle affects conditions directly in the tropical Pacific Ocean and affects the climate of other regions in the tropics and subtropics indirectly. Use examples of resulting weather patterns in specific locations and the resulting changes to productivity of marine ecosystems.
Appreciate that the frequency and intensity of both El Niño and La Niña events are irregular and hard to predict.
2.4.12 Tropical cyclones are rapidly circulating storm systems with a low-pressure centre that originate in the tropics and are characterized by strong winds.
Tropical cyclones are classified as hurricanes or typhoons (the name depends on where the storm originates in the world) once sustained wind speeds exceed 119 km/hr.
2.4.13 Rises in ocean temperatures resulting from global warming are increasing the intensity and frequency of hurricanes and typhoons because warmer water and air have more energy.
Include evidence for increases in hurricanes and typhoons.
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