Why isn't the day when the sun shines directly on the Tropic of Cancer the hottest day of the year?

The Tropic of Cancer is the longest day in a year, but the hottest day is the day with the largest ground radiation, because the temperature rises and the heat mainly comes from the ground radiation. The temperature is the highest only when the ground radiation is the strongest. Solar radiation is absorbed by the ground, which stores heat and releases it at the same time. It will take some time for the heat transfer between the ground and the atmosphere to reach the highest value in July. The day when the sun shines directly on the Tropic of Cancer is not July, so it is not the hottest day.