Nothing - the length of 'day' on any planet - is the time it takes to revolve once on its axis. Relating to the Earth - that's approximately 23 hours 56 minutes.
There would be no seasons, and the length of day & night would be exactly 12 hours each.
If there was no atmosphere, there would be no air for us to breathe, leading to suffocation and the inability for life to exist on Earth. Additionally, the lack of atmosphere would result in extreme temperature fluctuations between day and night, and increased exposure to harmful solar radiation.
Without the atmosphere, Earth would be exposed to harmful radiation from the sun, extreme temperatures fluctuations between day and night, and no protection from meteors entering the atmosphere. Life as we know it would not be able to exist without the atmosphere providing vital components like oxygen and a stable climate.
The length of the day would change if either the rotational speed of the the planet or the orbital distance from the sun changed. However, if you mean what factors affect the length of daylight, then that is different.
Without an atmosphere to distribute heat, temperature extremes between day and night on a celestial body would be significant. During the day, the surface exposed to the sun's rays would become extremely hot, while at night, without an atmosphere to trap heat, temperatures would plummet drastically. This phenomenon is observed on the moon, where temperatures range from about 127 degrees Celsius during the day to around -173 degrees Celsius at night.
With no atmosphere, there would be no "twilight". Twilight is caused by the scattering of sunlight in the atmosphere. With no atmosphere, you'd go from "day" to "night" with nothing in between.
Sunlight bounces around in the atmosphere, extending the length of the day both in the morning (before sunrise) and after sunset, roughly 30 minutes or so. Without an atmosphere it would be pitch black as soon as the sun set far enough for light to extinguish from any mountain slope eastward of you--the total day would be about an hour shorter.
If a day took 40 hours, then a day would take 40 hours.
In that case, the length of the day would also be approximately 40 hours.
It takes 24 hours (the length of one day) for the Earth to rotate once. If the rotation sped up, the length of a day would shorten.
The length of the day
There would be no seasons, and the length of day & night would be exactly 12 hours each.
A day would be a different length than 24 hours.
If there was no atmosphere, there would be no air for us to breathe, leading to suffocation and the inability for life to exist on Earth. Additionally, the lack of atmosphere would result in extreme temperature fluctuations between day and night, and increased exposure to harmful solar radiation.
Without the atmosphere, Earth would be exposed to harmful radiation from the sun, extreme temperatures fluctuations between day and night, and no protection from meteors entering the atmosphere. Life as we know it would not be able to exist without the atmosphere providing vital components like oxygen and a stable climate.
If there were no atmosphere on Earth, there would be no air for humans and most living creatures to breathe. The lack of atmosphere would also lead to extreme temperature fluctuations between day and night, and increased exposure to harmful solar radiation. Additionally, without the atmosphere, there would be no protection against meteoroids and space debris, making life on Earth unsustainable.
If polar ice melts, the day length will not be directly affected because day length is determined by the Earth's rotation on its axis, not the presence of ice at the poles. However, melting ice can contribute to rising sea levels and changes in the Earth's climate, which can have broader impacts on the environment and ecosystems.