References to the Triangular Symbolism of the Four Elements

Fire: Triangle points up   
Water: Triangle points down   
Air: Triangle points up with a horizontal line through center of triangle   
Earth: Triangle points down with a horizontal line through center of triangle

- Colors and Symbols of Four Elements, Feng-shui.lovetoknow.com

Each element is either warm or cold, and this corresponds with a male or female gender...The orientation of the triangle is determined by warmth or coldness, male or female. Male, warm elements point upward, ascending toward the spiritual realm. Female, cold elements point downward, descending into the earth.

- Four Elements and their Qualities, by Catherine Beyer, About.com


Each element has a symbol and color. Common symbols are Fire: a triangle pointing up.  Air: a triangle pointing up and with a horizontal line through the middle of it. Water: a triangle pointing down. Earth: a triangle pointing down and with a horizontal line through the middle of it.


- The Four Elements, Angelfire.com

The four classic elements are still essential symbols of the cultures and belief systems of many groups, including Native Americans, pagans and various tribal groups throughout the world...During the Greek Hellenic civilization (323-146 B.C.), the symbols used to represent the four elements of Greek physics were based on the triangle:
   
Fire: Triangle points up   
Water: Triangle points down   
Air: Triangle points up with a horizontal line through center of triangle   
Earth: Triangle points down with a horizontal line through center of triangle

- Colors and Symbols of Four Elements, Feng-shui.lovetoknow.com

Opposing elements are on opposite sides...and are distinguished by the presence or absence of the crossbar within the triangle...Air and earth are opposites and have the crossbar. Water and fire are also opposites, and lack the crossbar.

- Elemental Qualities, by Catherine Breyer, About.com

 

Fire: a triangle pointing up.
Air: a triangle pointing up and with a horizontal line through the middle of it.
Water: a triangle pointing down.
Earth: a triangle pointing down and with a horizontal line through the middle of it.

- The Four Elements, Angelfire.com