Pt 4 Struggle for existence reading Flashcards
Latitudinal Patterns and Temperature Gradients
Key Concept: The latitudinal gradient in temperature, driven by uneven solar energy distribution, is a primary source of ecological variation.
Cause: Earth’s spherical shape results in varied angles of solar radiation incidence:
Equator: Highest photon density; rays strike perpendicularly.
Poles: Low photon density; rays skim at shallow angles.
Significance: Affects organismal distribution and biodiversity patterns.
Seasonality:
Result of Earth’s axial tilt (23.5°) and orbit.
Tropics (23.5°N to 23.5°S):
-Defined by the Tropic of Cancer and Tropic of Capricorn.
-Solar equator oscillates annually between these lines, causing seasonal changes.
atmospheric circulation
Convection and Heat Transfer:
Earth’s atmosphere is heated from below, initiating convection currents.
Analogous to boiling water where heat at the base causes turbulent upward motion.
Hadley Cells:
Mechanism: Hot air rises at the equator (Intertropical Convergence Zone, ITCZ), cools, and descends at 30°N and 30°S.
Impacts:
Rainforests near the equator (low pressure, high rainfall).
Deserts at 30° (high pressure, dry descending air).
Ferrell and Polar Cells:
Ferrell Cells: Operate between 30° and 60°, driven by Hadley cells; contribute to mid-latitude precipitation zones.
Polar Cells: Weak circulation systems near the poles; cold, dry descending air.
Global Wind Patterns:
Hadley and Ferrell cells establish predictable wind patterns critical for climate and organism dispersal.
seasonal climate and precipitation patterns
Influence of ITCZ:
Shifts seasonally, creating alternating rainy and dry seasons in the tropics.
Greater latitude swings of ITCZ = more pronounced wet and dry periods.
Rain Shadow Effect:
Mechanism: Mountains block moist air, causing precipitation on the windward side and dry conditions on the leeward side.
biomes and climate
Biomes Defined:
Characterized by specific temperature and precipitation regimes.
Climate determines vegetation type and productivity (e.g., deserts, grasslands, forests).
Key Rules:
Precipitation: More water → taller, more species-rich vegetation.
Temperature: Warmer climates support more complex vegetation.
Soil-Climate Interaction:
Soil type and water availability affect vegetation, influencing biome characteristics.
Why does the equator receive the highest density of solar radiation?
Direct Sunlight: The equator is perpendicular to the Sun’s rays, concentrating solar energy over a smaller area.
Consistent Angle: Throughout the year, the equator experiences minimal variation in the Sun’s angle, maintaining high solar intensity.
Key Contrast: Higher latitudes receive sunlight at an angle, spreading energy over a larger area and reducing intensity.
Describe the role of the Hadley cell in establishing tropical rainforests and deserts.
Tropical Rainforests (Rising Air at the Equator):
The Hadley cell drives warm, moist air to rise at the equator.
Rising air cools, condenses, and forms heavy rainfall, creating lush, tropical rainforests.
Deserts (Sinking Air at 30° Latitude):
Air from the equator moves poleward and sinks around 30° latitude.
Sinking air is dry (moisture was lost at the equator), leading to arid conditions and the formation of deserts like the Sahara.
Summary: Rising air at the equator supports rainforests, while sinking air at 30° latitude creates deserts.
Why does the equator receive more solar radiation than the poles?
A: Solar rays hit the equator perpendicularly, concentrating energy, while at the poles, rays skim at shallow angles, spreading energy over a larger area.
What causes the latitudinal temperature gradient?
A: The spherical shape of the Earth, leading to uneven solar radiation distribution.
How does Earth’s axial tilt influence seasonality?
A: The 23.5° tilt causes varying solar radiation across latitudes throughout the year, creating seasons.
What defines the tropics?
A: The region between the Tropic of Cancer (23.5°N) and Tropic of Capricorn (23.5°S), characterized by high solar input and seasonal changes.
What are Hadley cells, and where do they occur?
A: Circulation cells between 0° and 30° latitude, where warm air rises at the equator, cools, and descends at 30°, creating rainforests and deserts
What creates deserts at 30° latitude?
A: Dry air descends in the Hadley cells, creating high-pressure zones with minimal rainfall.
How do Ferrell cells contribute to mid-latitude climates?
A: They circulate air between 30° and 60°, transporting warm air poleward and cold air equatorward, leading to temperate climates.
What are polar cells, and how do they impact the poles?
A: Circulation cells between 60° and 90° latitude; cold air sinks at the poles and flows toward 60°, creating dry, cold climates.
How do atmospheric cells drive global wind patterns?
A: They create predictable wind systems, such as trade winds and westerlies, influencing weather and species dispersal.
