Temperature at upper layer of troposphere is

Options

A. `-15^(@)C`
B. `-25^(@)C`
C. `-40^(@)C`
D. `-57^(@)C`.

Answer

To determine the temperature at the upper layer of the troposphere, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Troposphere**:
- The troposphere is the lowest layer of Earth's atmosphere, where most weather phenomena occur. It extends from the Earth's surface up to about 8 to 15 kilometers in altitude, depending on geographical location.

2. **Temperature Gradient**:
- In the troposphere, the temperature generally decreases with an increase in altitude. This is known as the environmental lapse rate.

3. **Temperature at the Upper Boundary**:
- At the uppermost boundary of the troposphere, known as the tropopause, the temperature can reach very low values. According to the transcript, the temperature at this boundary is approximately -54 degrees Celsius.

4. **Choosing the Closest Option**:
- The options provided are:
- A) -15 degrees Celsius
- B) -25 degrees Celsius
- C) -40 degrees Celsius
- D) -57 degrees Celsius
- Since -54 degrees Celsius is closest to -57 degrees Celsius, we choose -57 degrees Celsius as the correct answer.

5. **Final Answer**:
- Therefore, the temperature at the upper layer of the troposphere is approximately -57 degrees Celsius.