F3_2425_U3.1.pptx_s1-29 (1)

TAMING THE SAND

What is a Desert?

  • Definition: A desert is characterized as a dry area with annual rainfall of less than 250mm.

  • Climatic Conditions: Deserts have minimal cloud cover, large daily temperature variations, and unreliable rainfall.

  • Coverage: Deserts occupy about one-third of the Earth's land surface.

  • Aridity Impact: The low water availability impacts the types of life and landforms found in deserts.

Topics Covered

  • What and where are deserts?

  • The role of nature in desertification.

  • Strategies for combatting desertification.

Characteristics of Desert Climate

  • Temperature and Rainfall Overview:

    • Annual rainfall varies significantly across deserts.

    • Distinct seasonal temperature variations affect environments.

  • Faya-Largeau Climate Example:

    • Annual rainfall: 18mm.

    • Highest temperature: 34°C in June.

    • Lowest temperature: 20°C in January.

    • Annual temperature range: 14°C.

Types of Deserts

Major Deserts Include:

  • Sahara - Worlds largest tropical desert.

  • Atacama - Most arid desert on earth.

  • Antarctica - Largest desert overall, covering 14 million km².

  • Other notable deserts: Namib, Kalahari, Mojave, Sonoran, and Gobi.

Geographic Distribution of Deserts

  • Tropical Deserts: Located around 23.5°N/S latitude.

  • Temperate Deserts: Found in higher latitudes (~40°N/S).

  • The Arctic and Antarctica are categorized as deserts due to their low precipitation.

  • Desert Latitude Details:

    • Most deserts are found between 0° and 30° latitude.

Features of Desert Environments

Three Types of Deserts:

  1. Sandy Deserts:

    • Example: Namib.

    • High sand dunes (up to 400 meters).

    • Sand sourcing: erosion of rocks.

  2. Stony Deserts:

    • Example: Mojave.

    • Characterized by desert pavements (flat areas of stones).

  3. Rocky Deserts:

    • Found in regions like the Sahara.

    • Consists of rocky formations and landscapes.

Unique Landforms

  • Rock Pedestal: Formed from erosion of less resistant rock.

  • Yardangs: Shaped by wind abrasion, exhibit undercut features.

  • Sand Dunes: Barchan dunes, longitudinal, and star dunes present varying shapes influenced by wind direction.

Desert Vegetation Characteristics

  • Adaptations for Survival:

    • Small or no leaves to minimize water loss.

    • Fleshy stems for water storage.

    • Waxy surfaces to reflect sunlight.

    • Extensive root systems for greater water absorption.

    • Protective spikes to deter herbivores.

  • Oasis Locations: Vegetation is often found in oases where water is accessible, supporting unique ecosystems.

Conclusion

  • Environmental Impacts: The transformation and persistence of desert landscapes are influenced by climatic conditions and human activities.