Gamma

For Latin ɣ, see Latin gamma. For other uses, see Gamma (disambiguation).

Greek alphabet
Αα	Alpha	Νν	Nu
Ββ	Beta	Ξξ	Xi
Γγ	Gamma	Οο	Omicron
Δδ	Delta	Ππ	Pi
Εε	Epsilon	Ρρ	Rho
Ζζ	Zeta	Σσς	Sigma
Ηη	Eta	Ττ	Tau
Θθ	Theta	Υυ	Upsilon
Ιι	Iota	Φφ	Phi
Κκ	Kappa	Χχ	Chi
Λλ	Lambda	Ψψ	Psi
Μμ	Mu	Ωω	Omega
History
Archaic local variants  ·  ·  ·  ·  ·
Ligatures (ϛ, ȣ, ϗ) · Diacritics
Numerals: (6) · (90) · (900)
In other languages
Bactrian  · Coptic  · Albanian
Scientific symbols
Book  · Category · Commons

Gamma (uppercase Γ, lowercase γ; Greek: γάμμα) 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 Г and Ґ.

Uses

Greek

The alphabet on a black figure vessel, with a Λ-shaped gamma.

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.

Math and science

Lower case

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

• chromatic number of a graph. Sometimes χ is used, which is unfortunate since this is also used for the Euler characteristic
• gamma radiation in nuclear physics
• 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 onemicrogram (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 Euler–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: $\dot \gamma$
  • Austenite (also known as γ-iron), a metallic non-magnetic allotrope or solid solution of iron.

Upper case

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

• In mathematics, the gamma function (usually written as Γ-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

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

description	character	Unicode	HTML
Latin
LETTER GAMMA	Ɣ ɣ	U+0194 U+0263	Ɣ ɣ
International Phonetic Alphabet
SMALL LETTER RAMS HORN	ɤ	U+0264	ɤ
spacing modifier letters
MODIFIER LETTER SMALL GAMMA	◌ˠ	U+02E0	ˠ
Greek
LETTER GAMMA	Γ γ	U+0393 U+03B3	Γ γ
phonetic extensions
LETTER SMALL CAPITAL GAMMA	ᴦ	U+1D26	ᴦ
MODIFIER LETTER SMALL GAMMA	◌ᵞ	U+1D5E	ᵞ
SUBSCRIPT SMALL LETTER GAMMA	◌ᵧ	U+1D67	ᵧ
letterlike symbols
DOUBLE-STRUCK GAMMA	ℾ ℽ	U+213E U+213D	ℾ ℽ
Coptic
LETTER GAMMA	Ⲅ ⲅ	U+2C84 U+2C85	Ⲅ ⲅ

See also

• Г, г - Ge (Cyrillic)
• G, g - Latin
• photon