The intensity of the sun's rays is greatest at solar noon, which is the time of day when the sun reaches its highest point in the sky. This typically occurs around midday, but the exact time can vary depending on your location and the time of year.

Here's why:

* Angle of Incidence: The sun's rays hit the Earth at a more direct angle at solar noon. This means the same amount of energy is spread over a smaller area, resulting in a higher intensity.

* Atmospheric Absorption: As the sun's rays travel through the atmosphere, they are scattered and absorbed. This absorption is less at solar noon because the rays travel through less atmosphere to reach the ground.

However, it's important to note that the intensity of the sun's rays can also be affected by:

* Cloud cover: Clouds can block and reflect sunlight, reducing its intensity.

* Time of year: The sun's rays are more intense during the summer months when the Earth is tilted towards the sun.

* Latitude: The sun's rays are more intense at the equator than at the poles.

So, while solar noon is generally the time of greatest intensity, other factors can influence the actual amount of sunlight reaching the Earth's surface.