What each lightning symbol really is
🗲 is a text symbol officially named "lightning mood", added in Unicode 7.0. It is a bold, solid bolt that takes your text color, but older devices may show an empty box. ⚡︎ is the "high voltage sign" and the standard lightning emoji, so it shows in yellow almost everywhere.
ϟ is not a weather symbol at all: it is the Greek small letter koppa, an archaic letter that survives as the Greek numeral for 90. Its zigzag shape is why fans use it for Harry Potter's scar. Ϟ is the capital form.
☇ (lightning) and ☈ (thunderstorm) are old weather signs from the first version of Unicode. ↯ is a downward zigzag arrow that some mathematicians use to mark a contradiction, and ⌁ is the "electric arrow".
Which lightning bolt to use
For a bold bolt that matches your font, use 🗲. For the widest support, use ϟ, which nearly every font can show. For a colorful bolt in chats, use ⚡︎: it is the one people send for energy, speed, charging or hype.
Lightning works well next to clouds: ☁︎ ϟ ☁︎ makes a tiny text storm. Combine it with the fire symbol for a high-energy bio, or with ⚠︎ from the warning symbols for electrical hazards.
How to type a lightning bolt
On Windows, press Windows + . and search for "lightning" or "voltage" to get ⚡︎. On a Mac, press Control + Command + Space. On iPhone and Android, search the emoji keyboard for "lightning".
In Microsoft Word, type 03DF and press Alt + X for ϟ, or 26A1 for ⚡︎. The HTML code of every bolt is in the table below, and more Greek letters are on the Greek letters page.