$3,300$ and above Wurch/Kur Alpine or Afro-Alpine $<10$ $2,300 - 3,300$ Dega Temperate $10 - 15$ $1,500 - 2,300$ Woina Dega Subtropical $15 - 20$ $500 - 1,500$ Kolla Tropical $20 - 30$ Below $500$ Bereha Desert $> 30$

4.1 Characteristics of Zones

Wurch-Zone Areas: Highest altitudes, lowest temperatures ($<10^\circ C$). E.g., Mt. Ras Dashen, Mt. Batu.
Dega-Zone Areas: Highland areas, lower altitudes and higher temperatures than Wurch. Historically concentrated human settlement due to secure location, reliable rainfall, absence of tropical diseases. High soil erosion/overgrazing.
Woina-Dega-Zone Areas: Contain most agricultural land, main grain-producing areas. High rainfall reliability.
Kolla Zone Areas: Warm-to-hot semi-arid climate (tropical lowlands, $500-1500$ m.a.s.l.). Temperatures $20-30^\circ C$. Rainfall $410-820$ mm, highly variable. E.g., Western lowlands.
Bereha-Zone Areas: Hot arid climate (desert lowlands, below $500$ m.a.s.l.). Temperatures $>30^\circ C$. Rainfall $<400$ mm. Strong wind, high temp, low humidity, little cloud cover. Evapotranspiration exceeds rainfall. E.g., Danakil Depression.

5. Seasonal Variation in Ethiopia

Seasons are defined by Earth's axis inclination and revolution around the sun.

5.1 Seasonal Variation of Temperature

High temperatures: March-June.
Low temperatures: November-February.
Variations due to: Earth's tilt ($23.5^\circ$), overhead sun's apparent north-south movement.
Bega Season (Northern Hemisphere Winter): Clear skies, intense solar radiation. High diurnal temperature range (day-night difference).
Mean maximum temperatures: Western, northeastern, southeastern lowlands.
Lowest temperatures: Semein and Arsi-Bale mountains.
Highest temperature ($>45^\circ C$): Danakil Depression (hottest place).

5.2 Seasonal Variation of Rainfall

Ethiopia experiences marked spatial and temporal rainfall variations.

A. Spatial Variation of Rainfall

Result of Inter-Tropical Convergence Zone (ITCZ) oscillation, overhead sun movement, prevailing winds, and barrier effects.

ITCZ: Low atmospheric pressure zone, convergence of northeasterly and southeasterly trade winds. Shifts north and south following overhead sun.
- June (Tropic of Cancer): Ethiopia under Equatorial Westerlies and Easterlies, bringing moisture to highlands. Rain decreases northward.
- December (Tropic of Capricorn): Northeast Trade winds (dry, continental origin) prevail. Lowland areas near coast (Afar) receive some rain from Red Sea moisture. Dry season for most of Ethiopia.
- March & September (Equator): Equatorial Easterlies bring rain to southeastern lowlands, central and highlands.

B. Temporal Variation of Rainfall

Kiremt (Summer): June-August.
Belg (Spring): March-May.
These two contribute $>90\%$ of rain supply.
Meher (Autumn): September-November. Less duration, volume, and coverage than Kiremt/Belg.
Bega (Winter): December-February. Gener