The basis of astrological interpretation is the aspect, the angular relationship between the planets. Astrologers talk of squares, trines or oppositions, which relate to 90º, 120º and 180º respectively, but these degrees between the planets also define relationships between the signs of the zodiac and their elemental basis.
There is a strong correlation between Elemental Dignities and the elemental relationships defined by aspects in Astrology. The six major aspects in astrology can be seen as defining the relationships between the four elements and the 12 signs.
The characteristics below are from natal and transit astrology.
Unifying energies. An invading energy becomes dominant. One planet swallows another.
A tug of war, challenges from others. Something or someone is making the querent make a decision. Blaming or learning from another.
Fire/Air: Emperor and Justice; Lust and Star; Art and Lovers (Dynamic, combative, active)
Water/Earth: Hierophant and Death; Chariot and Devil; Hermit and Moon (Passive, inertial)
Tension between the symbolism of the energies involved. Inner worries, sense of being attacked, self-induced worry. Events that force the querent into a new type of action, things that cannot be avoided.
Fire/Water: Emperor and Chariot; Lust and Death; Art and Moon
Air/Earth: Lovers and Hermit; Adjustment and Devil; Star and Hierophant
Rapid development of a situation due to the removal of obstacles.
Fire: Emperor, Lust, Art
Water: Chariot, Death, Moon
Air: Lovers, Adjustment, Star
Earth: Hierophant, Hermit, Devil
A supportive relationship. Encountering a chance which may or may not be used to gain what is needed. Earth/Water sextiles show opportunities that fall into the querent's life which may or may not be taken up. Air/Fire sextiles show opportunities that are enthusiastically taken up.
Fire/Air: Emperor and Lovers; Lust and Adjustment; Art and Star
Water/Earth: Chariot and Hermit; Death and Devil; Moon and Hierophant
Tensions, misalignment, irritations, adjustment. Moving into a new situation - change or release. The quincunx is considered to be a "soft" aspect. Relationships that seem to have no logical connection but are difficult to change due to a want of sufficient energy to do so. Energies that work independently of one another in a conflicting manner. Routine annoyances and tensions in life.
Fire/Earth: Emperor and Hermit; Lust and Devil; Art and Hierophant
Water/Air: Cancer and Star; Death and Lovers; Moon and Adjustment