In meteorology, which of the following conditions is a key cause in the formation of tornadoes?

Introduction / Context:
This question comes from weather science and meteorology. Tornadoes are violently rotating columns of air extending from thunderstorms to the ground. Understanding the conditions that lead to tornado formation helps in weather prediction and safety planning.

Given Data / Assumptions:
- Several atmospheric conditions are listed: condensation, dry climates, wind shear, and stationary fronts. - The task is to choose the main cause associated with tornado formation. - Basic knowledge of severe thunderstorms is assumed.

Concept / Approach:
Wind shear refers to a change in wind speed or direction with height. In supercell thunderstorms, strong vertical wind shear can cause the updraft to rotate, which is a critical step in tornado formation. While moisture, instability, and lifting mechanisms are also needed, wind shear is the specific factor that organizes storms and helps create rotation.

Step-by-Step Solution:
1. Condensation is involved in cloud formation generally but is not the unique cause of tornadoes. 2. Dry climates can produce dust devils, but strong tornadoes are usually associated with moist, unstable air masses. 3. Stationary fronts can be involved in storm development but are not the direct cause of tornado rotation. 4. Wind shear, especially vertical wind shear, helps create horizontal vortices which can be tilted into the vertical by updrafts. 5. This vertical rotation can intensify and form a tornado under the right conditions. 6. Therefore, wind shear is the key cause listed here.

Verification / Alternative check:
Meteorology texts and severe weather training materials emphasize that a combination of instability and strong vertical wind shear is typical for environments that produce supercells and tornadoes. This confirms the importance of wind shear.

Why Other Options Are Wrong:
Condensation: Necessary for cloud and storm formation but too general to explain tornadoes specifically. Dry climates: Tornado producing storms usually require moist, unstable air, not dry conditions alone. Stationary fronts: Can provide lifting and boundaries, but without wind shear, tornadoes are less likely.

Common Pitfalls:
Students may think any dramatic weather term such as front or condensation is the main cause of tornadoes. Focusing on the role of wind shear in creating storm rotation helps to select the correct answer quickly.

Final Answer:
The condition that is a key cause of tornado formation is Wind shear.