Of course, if you happen to live in a location whose solar time is used as the basis for civil time in your time zone, solar noon will happen at or around 12 o'clock for you. When is solar noon in your city? Elastic Solar Time ![]() In many countries, Daylight Saving Time (DST) further increases the discrepancy between civil and solar time. This means that solar noon in western areas occurs later than 15:00 (3:00 pm) during some parts of the year, later than anywhere else on Earth. For example, China spans more than 60 degrees of longitude but the country follows a single time zone. Their borders are often grossly distorted by political or geographical factors. In real life, this difference is even larger because time zones rarely follow this ideal. Even if time zones were used the way they were once envisioned-where local time is based on the solar time in the zone's center, with the time zone extending 7.5 degrees of longitude to the west and to the east of the center line-solar noon would occur at 11:30 (11:30 am) at the eastern time zone border and at 12:30 (12:30 pm) at the western border. This means that clocks in the eastern part of each time zone show an earlier time at solar noon than clocks near its western border. While this undeniably makes life easier for us, it does not reflect the even movement of the Earth's rotation and the gradual geographical progression of local solar time. Since our clocks are set according to time zones, civil time changes abruptly as you move from one time zone to another, usually in 1-hour increments. In other words, solar noon happens a little earlier in locations just east of you and a little later in locations west of you. The Earth's rotation slowly shifts the meridian experiencing solar noon from east to west. In most places on Earth, solar noon does not happen at 12 o'clock. Since solar time depends on the longitude, solar noon occurs at exactly the same moment in all locations that share your local meridian. ![]() At this moment, it appears due south, due north, or in the zenith position exactly above you, depending on your latitude and the time of year. From your perspective, the Sun, after having steadily gained altitude since sunrise, now reaches the top of the arch that its journey describes in the sky every day. Solar noon happens at your location when the Earth's rotation brings your local meridian to the side of the planet that faces the Sun. ![]() The line running from one pole to the other via your location is your local meridian. It connects all locations that share the same longitude, meaning that they are exactly north or south of each other. This version of noon is also called solar noon or high noon.Ī meridian is an imaginary line running from the North Pole to the South Pole along the Earth's surface. In terms of solar time, noon is the moment when the Sun crosses the local meridian and reaches its highest position in the sky, except at the poles.Alternative names include midday and noon time. In terms of civil time, noon is simply another word for 12 o'clock, the moment separating morning and afternoon.The English language is a little imprecise when it comes to the word “noon”. Business Date to Date (exclude holidays).
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