Definition

1. Noun:
   • A luminous halo parallel to the horizon at the altitude of the sun; caused by ice crystals in the atmosphere: A "solar halo" is an optical phenomenon appearing as a bright, often white or colored, ring or arc of light in the sky. It runs parallel to the horizon at the same altitude as the sun and is created by the refraction and reflection of sunlight through hexagonal ice crystals suspended in cirrus or cirrostratus clouds.

Usage

• The term "solar halo" is used specifically in meteorology and atmospheric science to describe this particular optical effect. It is a technical term but is also commonly used by weather observers and photographers.
• It is typically used as a countable noun (e.g., , ).

Examples

• Noun:
  • We observed a brilliant solar halo around the sun this afternoon.
  • The appearance of a solar halo is often a sign that cirrus clouds are present and weather may change.
  • Photographers waited for hours to capture the perfect solar halo.

Advanced Usage

• "To see/form a solar halo": Used to describe the observation or formation of the phenomenon.
  • A perfect solar halo formed around the sun just before the storm arrived.
• In scientific contexts, it may be discussed in relation to other halo phenomena, such as sun dogs (parhelia) or circumzenithal arcs, which are caused by similar ice crystal interactions.

Variants and Related Words

• Halo (n): A more general term for a ring of light around a luminous body, which can be caused by various atmospheric conditions or in other contexts (e.g., religious art).
• Sun dog / Parhelion (n): A related bright spot that sometimes appears on a solar halo.
• Circumhorizontal arc (n): A similar, colorful optical phenomenon caused by ice crystals, but it appears as a band parallel to the horizon, often below the sun.
• Ice crystal halo (n): A broader term encompassing all halo phenomena caused by ice crystals.

Synonyms

• Sun halo: A common, less technical synonym.
• 22° halo: A specific scientific term referring to the most common type of solar halo, which has a radius of approximately 22 degrees around the sun.

Related Phrases

• Ring around the sun: A descriptive, non-technical phrase for a solar halo.
  • Look, there's a ring around the sun today.

Notes

• A "solar halo" is distinct from a "lunar halo," which forms around the moon via the same physical process.
• The phenomenon is often associated with approaching warm fronts and can be a predictor of precipitation within the next 12-24 hours.

Noun

1. a luminous halo parallel to the horizon at the altitude of the sun; caused by ice crystals in the atmosphere