A thermometer laid outside in the sun will measure the temperature of the thermometer itself, which will be influenced by both the air temperature and the sun's radiation.

Here's why:

* Direct Sunlight: The sun's rays directly heat the thermometer, causing its temperature to rise above the surrounding air temperature.

* Air Temperature: The air around the thermometer will also transfer heat to it, either warming or cooling it depending on the air temperature.

To get an accurate air temperature reading, you should:

* Shade the thermometer: This will prevent the sun's direct radiation from affecting the reading.

* Allow time for the thermometer to stabilize: The thermometer needs time to adjust to the surrounding air temperature.

In summary: While a thermometer in the sun will be affected by the sun's heat, it doesn't directly measure the sun's temperature. It's a combination of the sun's radiation and the surrounding air temperature that influences the reading.