Question

In an arid environment, winds of similar intensity blow in nearly opposite directions in alternate seasons. Which dune type is most likely to form in such an environment?

• A. Barkhan
• B. Transverse dunes
• C. Seif
• D. Lunate

Hint:

Seif dunes form in arid environments with alternating wind directions, creating long, narrow ridges aligned with the wind.

Answer 1

The Correct Option is C

Step 1: Understanding wind directions and dune formation.
In arid environments, the wind direction and intensity play a key role in the formation of different types of dunes. Winds blowing in opposite directions during alternate seasons create conditions favorable for seif dunes.
These dunes are long, narrow, and oriented parallel to the prevailing wind directions. They form when the wind direction changes seasonally, leading to a series of alternating ridges in the sand.

Step 2: Analyzing dune types.
- Barkhan dunes: These crescent-shaped dunes form when wind blows from one direction, making them typical of areas with a consistent prevailing wind direction.
- Transverse dunes: These dunes form perpendicular to the prevailing wind direction and are typically found in regions with steady, one-directional wind.
- Seif dunes: As explained earlier, these dunes form under conditions where wind blows from opposite directions in alternating seasons, creating long ridges aligned with the wind.
- Lunate dunes: These crescent-shaped dunes also form in regions with consistent wind, but they differ from Barkhan dunes in shape and size. They are less likely to form under alternating wind conditions.

Step 3: Conclusion.
The correct dune type for alternating wind directions in an arid environment is Seif dunes. Therefore, the correct answer is (C).
\[ \boxed{\text{Seif}} \]