Wind Patterns of the Sahara Desert

The Sahara's wind regime reflects its position under the subtropical high and tropical easterlies:

1. Northeast Trade Winds (Dominant)

Persistent easterlies from the Azores High → equatorial trough. Drive sand transport south-southwest. Create longitudinal dunes (seif) aligned with resultant drift direction.

2. Harmattan (Nov–Mar)

Dry, dusty northeasterly from Saharan high toward Gulf of Guinea. Carries 100–500M tonnes dust/year across West Africa to Atlantic. Reduces visibility, causes respiratory spikes, fertilizes Amazon.

3. Khamsin (Mar–May, Sep–Nov)

Hot, dry, sand-laden southerly/southeasterly ahead of Mediterranean lows. Affects Egypt, Libya, Levant. 50°C+ temps, visibility <100 m. "50-day wind" (Arabic: khamsin).

4. Simoom (Summer)

Extreme heat/dust wind in Arabia, Iraq, eastern Sahara. >50°C, near-zero humidity. Physiological threat: heatstroke, dehydration in minutes.

5. Jet Stream Influence

• Subtropical jet (STJ): Winter position over Sahara steers Mediterranean cyclones, modulates Khamsin
• African Easterly Jet (AEJ): ~600 hPa, 10–15°N. Drives easterly waves → Atlantic hurricanes
• Polar jet: Rarely reaches Sahara latitudes

6. Local/Mesoscale Winds

Sea breezes (coastal), slope/valley winds (Atlas, Hoggar, Tibesti), dust devils, haboobs (cold pool outflows from convection).

Wind is the Sahara's primary sculptor—eroding, transporting, depositing, and defining the surface geomorphology.