Types of meteors (WMO)

Ref : https://cloudatlas.wmo.int/en/general-classification-of-meteors.html

(4) Four types of meteors (WMO):

1. 水 moisture related

2. 光 light related

3. 電 electrical related

4. 塵 dust and particle related

Meteors present a great diversity of character. However, by considering their constituent particles or the physical processes surrounding their occurrence, meteors can be classified into four groups: hydrometeors, lithometeors, photometeors and electrometeors.

大氣現象呈現出多種多樣的特徵。但是，根據它們的組成粒子或它們發生期間的物理過程，大氣現象可以分為四組：水凝物、大氣塵粒現象、大氣光學現象 和 大氣電學現象。

Moisture related – hydrometeors

Note: Snow or water on the ground is, by convention, not considered a hydrometeor.

From the state of the moisture perspective – Hydrometeors consist of liquid or solid water particles. From the presenting form perspective – They may be suspended in the atmosphere, fall through the atmosphere, be blown by the wind from the Earth’s surface or be deposited on other objects.

We describe the following (5) five types of hydrometeors:

• Suspended particles – e.g cloud;

• Falling particles (precipitation) – e.g rain/shower;

• Particles raised by the wind from the Earth’s surface – e.g fog;

• Deposits of particles – e.g ice or dew on plants;

• Spouts.

Light related – photometeor

A photometeor is an optical phenomenon produced by the reflection, refraction, diffraction or interference of light from the Sun or the Moon.

Photometeors can be:

• On or inside clouds: halo phenomena, corona, irisations and glory;
• On or inside some hydrometeors or lithometeors: halo phenomena, corona, glory, rainbow, Bishop’s ring and crepuscular rays;
• In clear air: mirage, shimmer, scintillation, green flash and twilight colours.

Electrical related – electrometeor

An electrometeor is a visible or audible manifestation of atmospheric electricity.

Electrometeors can be:

Related to discontinuous electrical discharges (lightning or thunder)
More or less continuous (Saint Elmo’s fire or polar aurora).

Dust and particle related – lithometeor

A lithometeor consists of an ensemble of particles, most of which are solid and non-aqueous. The particles are either suspended in the air or lifted by the wind from the ground.

Lithometeors can be:

Suspended particles (haze, dust haze or smoke ) consisting of very small dust particles, sea-salt particles or combustion products (for example, from forest fires)
Particles lifted by the wind ( drifting and blowing dust or sand, dust storm or sandstorm, and dust whirl or sand whirl). When well developed, a dust whirl is known as a dust devil.