Tema 2 Econ Geo

Earth Basics & Geometry

Key Earth Parameters

• Equatorial Diameter: 12,757 km

• Polar Diameter: 12,714 km (Earth is an oblate spheroid)

• Equatorial Circumference: 40,077 km

• Polar Circumference: 40,009 km

• Axial Inclination: 23.5° (obliquity of the ecliptic)

  • The angle between Earth's equatorial plane and its orbital plane (ecliptic).

  • Consequence: Creates seasons and unequal distribution of solar radiation across latitudes.

Seven Principal Tectonic Plates

#	Plate
1	Antarctic Plate
2	Pacific Plate
3	South American Plate
4	North American Plate
5	African Plate
6	Eurasian Plate
7	Australian-Indian Plate

Flashcard 2: Smaller Tectonic Plates

Region	Plates
Mediterranean / Middle East	Hellenic-Turkish Plate, Iranian Plate, Arabian Plate
Pacific / Americas	Juan de Fuca Plate, Caribbean Plate, Nazca Plate, Cocos Island Plate, Scotia Plate, Philippine Plate

Main Volcanic Zones of the Earth (5 Zones)

(5 Zones)

Zone	Key Examples
1. Pacific Ring of Fire	Most active zone; includes Kamchatka (Klyuchevskaya Sopka), Japan, Andes, Cascades
2. Mid-Atlantic Ridge	Iceland, Azores; divergent plate boundary
3. East African Rift Valley	Kilimanjaro, Nyiragongo; continental rift zone
4. Mediterranean-Alpine Belt	Vesuvius, Etna, Santorini; collision zone
5. Intraplate Hotspots	Hawaii (Mauna Loa), Yellowstone, Canary Islands

Volcanic Zones – Recognition

Volcano	Location	Zone
Klyuchevskaya Sopka	Kamchatka, Russia	Pacific Ring of Fire
Mauna Loa	Hawaii, USA	Intraplate Hotspot
Vesuvius / Etna	Italy	Mediterranean-Alpine Belt
Eyjafjallajökull	Iceland	Mid-Atlantic Ridge
Kilimanjaro	Tanzania	East African Rift

Post-Volcanic Phenomena – Definitions

Type	Temperature	Characteristics
Fumarola	~200°C	Mineral-rich water vapor eruptions
Solfatara	~100–200°C	Water vapor containing hydrogen sulfide (H₂S) and sulfur dioxide (SO₂); sulfur deposits
Mofetta	0–100°C	Dry carbonic acid vapor (CO₂); no water vapor
Geyser	Varies	Intermittent hot water eruptions; natural hot springs

Atmospheric Layers – Order & Boundaries (Bottom to Top)

Layer	Altitude Range	Key Characteristics
Troposphere	0–16 km	Weather forms; contains 75% of atmosphere; temperature decreases with altitude; extends 8 km at poles, 16 km at equator; top temp: -75°C
Stratosphere	16–50 km	Ozone layer peaks at ~22 km; contains 20% of atmospheric molecules; temperature increases with altitude
Mesosphere	50–80 km	Meteors burn up ("shooting stars"); coldest layer (as low as -90°C at top)
Thermosphere	80–640 km	Temperature rises (up to 230°C); contains ionosphere (charged particles) & magnetosphere; Northern & Southern Lights occur here
Exosphere	640–64,000 km	Farthest layer; air dwindles to nothing; molecules drift into space

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Earth's Energy Budget – Core Mechanism

• Incoming: Shortwave solar radiation passes through atmosphere

• Surface: Warms the Earth's surface

• Outgoing: Surface emits longwave terrestrial radiation

• Atmospheric Warming: Longwave radiation is absorbed by greenhouse gases (H₂O, CO₂, ozone) and clouds, warming the atmosphere/troposphere

Incoming Solar Radiation (100%)

Component	Percentage
Reflected/Scattered to Space	30% (total)
└ Reflected by clouds	17%
└ Reflected/scattered by atmosphere	7%
└ Reflected by surface	6%
Absorbed	70% (total)
└ Absorbed by atmosphere (air, H₂O, ozone, clouds, dust)	23%
└ Absorbed by Earth's surface	47%

Longwave Radiation (Outgoing)

Component	Percentage
Radiated from clouds	20%
Radiated from H₂O, ozone, CO₂	40%
Latent heat (evaporation/condensation)	24%
Conduction (surface to air contact)	7%
Longwave radiation escaping to space	6%

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Energy Budget – Summary

• Incoming: 100% shortwave solar radiation

• Reflected: 30% returned to space (albedo)

• Absorbed: 70% warms Earth system

• Atmospheric Warming: Primarily from absorbed longwave terrestrial radiation (greenhouse effect)

• Key Insight: The atmosphere is heated from the ground up—surface absorbs shortwave radiation, then emits longwave radiation that greenhouse gases trap

Key Terminology for Earth's Energy Budget

Term	Definition
Shortwave Radiation	Incoming solar radiation (visible light, UV)
Longwave Radiation	Outgoing terrestrial radiation (infrared)
Albedo	Reflectivity of a surface; Earth's average albedo is ~30%
Greenhouse Effect	Trapping of longwave radiation by atmospheric gases (H₂O, CO₂, O₃)
Latent Heat	Energy absorbed or released during phase changes (evaporation, condensation)
Conduction	Direct heat transfer between surface and air

Climate Zones Recognition

Zone	Latitude	Key Features
Tropical	0°–30°	High temperatures year-round; high precipitation (rainforest) or seasonal (savannah)
Temperate	30°–60°	Four distinct seasons; moderate temperatures; westerly winds dominate
Polar	60°–90°	Very cold; low precipitation; polar easterlies; permanent ice or tundra

Arid vs. Humid Climate

Arid vs. Humid Climate

Type	Definition	Characteristics
Arid Climate	Annual evaporation exceeds annual precipitation	Endorheic basins (no drainage to ocean); rivers lose water to evaporation or flow into impermeable lakes
Humid Climate	Total precipitation exceeds maximum possible evaporation	Excess removed as surface runoff (rivers flow to ocean)
Semi-Humid Climate	Evaporation exceeds precipitation for only a few months	Transitional between humid and arid

Climate Definitions

Term	Definition
Climate	Set of near-Earth atmospheric and weather processes affecting Earth's surface over a long period, specific to a place or region
Climate Elements	Measurable atmospheric phenomena: solar radiation, pressure, humidity, temperature, wind, evaporation, precipitation, cloud cover
Climate Factors	Surface features influencing climate: latitude, altitude, land cover, exposure
Climate Zones	Zonal areas with typical climatic characteristics; shaped by irradiation patterns and wind cycles; closely linked to vegetation zones

Climate Diagram

• Definition: A simplified graphic representation of the most important climate elements (primarily temperature and precipitation)

• Purpose: Primarily used to compare different climate types

• Typical Format: Red line (temperature), blue bars (precipitation), months on x-axis

Altitudinal Zonation – Key Principle

• Concept: As altitude increases, climate becomes colder and harsher, creating vegetation zones similar to those found at increasing latitudes (from tropical to polar)

• Rate: Temperature drops approximately 6.5°C per 1,000 m elevation (lapse rate)

• Alps (temperate zone): Shorter vertical sequence (base: temperate forest → top: snow)

• Himalayas (tropical zone): Longer vertical sequence (base: tropical forest → top: snow)

Altitudinal Zones – Mont Blanc (Alps) – From Bottom to Top

Altitude Zone	Vegetation
Lowest (foothills)	Hard-leaved forest and shrubs (Mediterranean influence)
	Chestnut forest, gardens, vines, crops
	Oak and beech forest
	Mixed forest
Mid-altitude	Conifer forest
High altitude	Alpine meadows and shrubs
	Mountain wastelands
Highest	Eternal snows

Atmospheric Circulation – Key Pressure Zones

Zone	Pressure	Air Movement
Equator (0°)	Low	Rising air (convergence)
Subtropics (~30°)	High	Descending air (divergence)
Subpolar (~60°)	Low	Rising air
Poles (90°)	High	Descending air

Global Wind Belts

Wind Belt	Latitude	Direction	Pressure System
Polar Easterlies	60° – 90°	East to west	High pressure at poles; low pressure at 60°
Westerlies	30° – 60°	West to east	Low pressure (rising air)
Northeast Trade Winds	0° – 30° N	From NE to SW	Descending air at 30°; rising air at Equator
Southeast Trade Winds	0° – 30° S	From SE to NW	Descending air at 30°; rising air at Equator

• Intertropical Convergence Zone (ITCZ): Zone of rising air at Equator; low pressure; heavy rainfall

Major Latitudinal Circles

Circle	Latitude
North Pole	90° N
Arctic Circle	66° 33' 39" N
Tropic of Cancer	23° 26' 22" N
Equator	0°
Tropic of Capricorn	23° 26' 22" S
Antarctic Circle	66° 33' 39" S
South Pole	90° S

• Prime Meridian: 0° longitude (runs through Greenwich, UK)

Number & Location of Climate Zones (3 main zones per hemisphere)

Zone	Latitude Range
Tropical Zone	0° – 30° N / S
Temperate Zone	30° – 60° N / S
Polar Zone	60° – 90° N / S

• Key Driver: Different irradiation patterns based on angle of incoming solar radiation

Equinoxes

Event	Date	Key Feature
Spring Equinox (Vernal)	March 21	Day and night equal length (12 hours) everywhere on Earth
Autumn Equinox	September 23	Day and night equal length (12 hours) everywhere on Earth

• During Equinoxes: The Sun is directly above the Equator; neither hemisphere is tilted toward or away from the Sun

Solstices

Event	Date	Northern Hemisphere	Southern Hemisphere
Summer Solstice	June 21	Summer (longest day, most direct sunlight)	Winter (shortest day)
Winter Solstice	December 21	Winter (shortest day)	Summer (longest day, most direct sunlight)

• During Solstices: One hemisphere is tilted maximally toward the Sun (summer), the other away (winter)

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Seasonal Process Explanation

• Cause: Earth's 23.5° axial tilt

• Effect: As Earth orbits the Sun, different hemispheres receive more direct solar radiation at different times of year

• Summer: Hemisphere tilted toward Sun → higher sun angle → more concentrated solar energy → warmer temperatures

• Winter: Hemisphere tilted away from Sun → lower sun angle → more dispersed solar energy → cooler temperatures