Tropopause is

Options

A. Lower portion of atmosphere
B. Upper part of troposhere
C. Middle part of troposphere
D. Lower part of troposphere

Answer

**Step-by-Step Solution:**

1. **Understanding the Atmosphere Layers**: The Earth's atmosphere is divided into several layers, with the troposphere being the lowest layer where all weather phenomena occur.

2. **Defining the Troposphere**: The troposphere extends from the Earth's surface up to a certain altitude. It is characterized by a decrease in temperature with increasing altitude.

3. **Identifying the Tropopause**: The tropopause is the boundary layer that separates the troposphere from the stratosphere. It marks the point where the temperature stops decreasing with altitude and starts to increase in the stratosphere.

4. **Analyzing the Options**:
- Option 1: Lower portion of atmosphere - Incorrect, as it refers to the entire atmosphere.
- Option 2: Upper part of troposphere - Correct, as the tropopause is indeed the upper boundary of the troposphere.
- Option 3: Middle part of troposphere - Incorrect, as the tropopause is not in the middle.
- Option 4: Lower part of troposphere - Incorrect, as it is not the lower part.

5. **Conclusion**: Based on the definitions and analysis, the correct answer is that the tropopause is the upper part of the troposphere.

**Final Answer**: The tropopause is the upper part of the troposphere.

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