When it is daytime in north America night time China why?

The reason for this difference is due to the rotation of the Earth on its axis and the Earth's orbit around the Sun.

As the Earth rotates on its axis, different parts of the planet are exposed to the Sun at different times. When it is daytime in North America, it is nighttime in China because China is on the opposite side of the Earth from North America.

In addition, the Earth's orbit around the Sun is not a perfect circle, but an ellipse. This means that the Earth's distance from the Sun varies throughout the year. When the Earth is closest to the Sun, it is called perihelion, and when it is furthest from the Sun, it is called aphelion.

The Earth's orbit also means that the amount of daylight varies throughout the year. In the summer, the days are longer and the nights are shorter, while in the winter, the days are shorter and the nights are longer. This is because the Earth's axis is tilted at an angle of 23.5 degrees. When the Northern Hemisphere is tilted towards the Sun, it receives more daylight, and when the Northern Hemisphere is tilted away from the Sun, it receives less daylight.

These factors all contribute to the difference in time between North America and China.