रेखांश
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| पृथ्वी का नक्शा | |
| रेखांश (λ) | |
|---|---|
| रेखांश की रेखाएं इस प्रक्षेप में वक्रीय प्रतीत होती हैं, परंतु ध्रुववृत्तों की आधी होती हैं। | |
| अक्षांश (φ) | |
| अक्षांश की रेखाएं इस प्रक्षेप में क्षैतिज एवं सीधी प्रतीत होती हैं, परंतु वे भिन्न अर्धव्यासों सहित वृत्तीय होती हैं। एक अक्षांश पर दी गईं सभी स्थान एकसाथ जुड़कर अक्षांश का वृत्त बनाते हैं। | |
| भूमध्य रेखा पृथ्वी को उत्तरी गोलार्ध और दक्षिणी गोलार्ध में बांटती है, और इसका अक्षांश शून्य अंश यानि 0° होता है। |  |
रेखांश (IPA: /ˡlɒndʒɪˌtjuːd/), जिसे यूनानी अक्षर लैम्बडा (λ) से दर्शित किया जाता है, पूर्व से पश्चिम पर्यन्त भूगोलीय निर्देशांक हैं, जिन्हें अधिकतर मानचित्रकला एवं भूमंडलीय नौवहन में प्रयोग किया जाता है। रेखांश की एक रेखा एक ध्रुववृत्तीय रेखा होती है, जो ध्रुववृत्त का आधा होती है।
इतिहास[संपादित करें]
रेखांश का आकलन[संपादित करें]
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यह सम्पूर्ण पृष्ठ या इसके कुछ विभाग हिन्दी के अतिरिक्त अन्य भाषा(ओं) में भी लिखे गए हैं। आप इनका करके विकिपीडिया की सहायता कर सकते हैं। |
Longitude is given as an angular measurement ranging from 0° at the prime meridian to +180° eastward and −180° westward. The Greek letter λ (lambda),[1][2] is used to denote the location of a place on Earth east or west of the prime meridian.
Each degree of longitude is sub-divided into 60 minutes, each of which divided into 60 seconds. A longitude is thus specified in sexagesimal notation as 23° 27′ 30" E. For higher precision, the seconds are specified with a decimal fraction. An alternative representation uses degrees and minutes, where parts of a minute are expressed in decimal notation with a fraction, thus: 23° 27.500′ E. Degrees may also be expressed as a decimal fraction: 23.45833° E. For calculations, the angular measure usually must be converted to radians, so longitude may also be expressed in this manner as a signed fraction of π (pi), or an unsigned fraction of 2π.
For calculations, the West/East suffix is replaced by a negative sign in the western hemisphere. Confusingly, the convention of negative for East is also sometimes seen. The preferred convention—that East be positive—is consistent with a right-handed Cartesian coordinate system with the North Pole up. A specific longitude may then be combined with a specific latitude (usually positive in the northern hemisphere) to give a precise position on the Earth's surface.
Longitude at a point may be determined by calculating the time difference between that at its location and Coordinated Universal Time (UTC). Since there are 24 hours in a day and 360 degrees in a circle, the sun moves across the sky at a rate of 15 degrees per hour (360°/24 hours = 15° per hour). So if the time zone a person is in is three hours ahead of UTC then that person is near 45° longitude (3 hours × 15° per hour = 45°). The word near was used because the point might not be at the center of the time zone; also the time zones are defined politically, so their centers and boundaries often do not lie on meridians at multiples of 15°. In order to perform this calculation, however, a person needs to have a chronometer (watch) set to UTC and needs to determine local time by solar observation or astronomical observation. The details are more complex than described here: see the articles on Universal Time and on the Equation of time for more details.
| Latitude | N-S radius of curvature,  |
Degree of latitude |
E-W radius of curvature,  |
Degree of longitude |
|
|---|---|---|---|---|---|
| 0° | 6335.44 km | 110.574 km | 6378.14 km | 111.320 km | |
| 15° | 6339.70 km | 110.649 km | 6379.57 km | 107.551 km | |
| 30° | 6351.38 km | 110.852 km | 6383.48 km | 96.486 km | |
| 45° | 6367.38 km | 111.132 km | 6388.84 km | 78.847 km | |
| 60° | 6383.45 km | 111.412 km | 6394.21 km | 55.800 km | |
| 75° | 6395.26 km | 111.618 km | 6398.15 km | 28.902 km | |
| 90° | 6399.59 km | 111.694 km | 6399.59 km | 0.000 km |
टिप्पणी[संपादित करें]
- ↑ Coordinate Conversion
- ↑ "λ = Longitude east of Greenwich (for longitude west of Greenwich, use a minus sign)."
John P. Snyder, Map Projections, A Working Manual, USGS Professional Paper 1395, page ix
देखें[संपादित करें]
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बाहरी कडि़यां[संपादित करें]
- Resources for determining your latitude and longitude
- Worldwide Index - Tageo.com – contains 2,700,000 coordinates of places including US towns
- for each city it gives the satellite map location, country, province, coordinates (dd,dms), variant names and nearby places.
- IAU/IAG Working Group On Cartographic Coordinates and Rotational Elements of the Planets and Satellites
- Latitude and longitude converter – Convert latitude and longitude from degree, decimal form to degree, minutes, seconds form and vice versa. Also included a farthest point and a distance calculator.
