Gamma

Gamma (uppercase Î", lowercase γ; Greek: Î"άμμα Gámma) is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. It was derived from the Phoenician letter Gimel . Letters that arose from gamma include the Roman C and G and the Cyrillic letters Ð" and Ґ.

Uses

Greek

In Ancient Greek, gamma represented a voiced velar stop /ɡ/. In Modern Greek, it represents a voiced fricative. It is realized either as a palatal /ʝ/ (before a front vowel, /e, i/), or as a velar /ɣ/ (in all other environments).

Both in Ancient and in Modern Greek, before other velars (κ, χ, ξ k, kh, ks), gamma represents a velar nasal /ŋ/. A double gamma γγ represents the sequence /ŋɡ/ (phonetically varying [ŋɡ~ɡ]) or /ŋɣ/.

International Phonetic Alphabet

In the International Phonetic Alphabet, lowercase gamma (ɣ) represents the voiced velar fricative. A lowercase gamma that lies above the baseline rather than crossing it (ɤ) represents the close-mid back unrounded vowel.

Mathematics and science

Lower case

The lower-case letter is used as a symbol for:

• Chromatic number of a graph, sometimes (Chi) is used, which is also used for the Euler characteristic
• Gamma radiation in nuclear physics
• The photon, the elementary particle of light
• Surface energy in materials science
• The Lorentz factor in theory of relativity
• The heat capacity ratio Cp/Cv in thermodynamics
• The activity coefficient in thermodynamics
• The gyromagnetic ratio in electromagnetism
• Gamma oscillation in neuroscience
• Gamma motoneurons in neuroscience
• Gamma is a non-SI metric unit of measure of mass equal to one microgram (1 μg). This always-rare use is currently deprecated.
• Gamma is also a non-SI unit of measure of magnetic flux density, sometimes used in geophysics, equal to 1 nanotesla (nT).
• The power by which the luminance of an image is increased in gamma correction
• The Eulerâ€"Mascheroni constant
• In mechanical engineering:
  • Specific weight
  • The shear rate of a fluid is represented by a lower case gamma with a dot above it:
  • Austenite (also known as γ-iron), a metallic non-magnetic allotrope or solid solution of iron.
• The gamma carbon is the third carbon attached to a functional group in Organic Chemistry and Biochemistry nomenclature; see Alpha and beta carbon

Upper case

The upper-case letter is used as a symbol for:

• In mathematics, the gamma function (usually written as -function) is an extension of the factorial to complex numbers
• In probability theory and statistics, the gamma distribution is a two-parameter family of continuous probability distributions.
• Circulation in fluid mechanics
• As reflection coefficient in physics and electrical engineering
• The tape alphabet of a Turing machine
• The Fefermanâ€"Schütte ordinal Î"₀

Meteorology

• Gamma was one of the names used in the 2005 Atlantic hurricane season as Tropical Storm Gamma.

Technical notes

HTML

The HTML entities for uppercase and lowercase gamma are Γ and γ.

Unicode

• Greek Gamma

• Coptic Gamma

• Latin / phonetic Gamma

• CJK Square Gamma

• Technical / Mathematical Gamma

These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.

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