Air is one of the four classical elements, and is often invoked in Wiccan ritual. Air is the element of the East, connected to the soul and the breath of life. Air is associated with the colors yellow and white. Interestingly, in some cultures a triangle sitting on its base like this is considered masculine, and is connected to the element of Fire rather than Air.
In some traditions of Wicca, Air is represented not by the triangle, but by either a circle with a point in the center, or by a feather or leaf-like image. In other traditions, the triangle is used to mark the association of degrees or initiation rank -- typically first degree, but not necessarily. In alchemy, this symbol is sometimes show with the horizontal line extending beyond the sides of the triangle.
In rituals, when the element of Air is called for, you can use this triangular symbol, or use a feather, incense, or a fan. Air is associated with communication, wisdom or the power of the mind. Do an outdoors working on a windy day, and allow the powers of air to aid you. Visualize air currents carrying away your troubles, blowing away strife, and carrying positive thoughts to those who are far away. Embrace the wind, and let its energy fill you and help you achieve your goals.
In many magical traditions, air is associated with various spirits and elemental beings. Entities known as sylphs are typically connected with the air and the wind - these winged creatures are often related to powers of wisdom and intuition. In some belief systems, angels and devas are associated with air. It should be noted that the term “deva” in New Age and metaphysical studies is not the same as the Buddhist class of beings known as devas.
Read more about the magic, mythology, and folklore of air and the wind: Air and Wind Folklore.