Rudra, is a mixed color of blue (ignorance) and red (passion), because anger is the product of passion and ignorance.
In Bhagavad-gita (3.37) the principle of Rudra is described. Krodha (anger) is the product of kama (lust), which is the result of the mode of passion. When lust and hankering are unsatisfied, the element of krodha appears, which is the formidable enemy of the conditioned soul. This most sinful and inimical passion is represented as ahankara, or the false egocentric attitude of thinking oneself to be all in all. Such an egocentric attitude on the part of the conditioned soul, who is completely under the control of material nature, is described in Bhagavad-gita as foolish. The egocentric attitude is a manifestation of the Rudra principle in the heart, wherein krodha (anger) is generated. This anger develops in the heart and is further manifested through various senses, like the eyes, hands and legs. When a man is angry he expresses such anger with red-hot eyes and sometimes makes a display of clenching his fists or kicking his legs. This exhibition of the Rudra principle is the proof of Rudra’s presence in such places. When a man is angry he breathes very rapidly, and thus Rudra is represented in the air of life, or in the activities of breathing. When the sky is overcast with dense clouds and roars in anger, and when the wind blows very fiercely, the Rudra principle is manifested, and so also when the sea water is infuriated by the wind it appears in a gloomy feature of Rudra, which is very fearful to the common man. When fire is ablaze we can also experience the presence of Rudra, and when there is an inundation over the earth we can understand that this is also the representation of Rudra.
There are many earthly creatures who constantly represent the Rudra element. The snake, tiger and lion are always representations of Rudra. Sometimes, because of the extreme heat of the sun, there are cases of heatstroke, and due to the extreme coldness created by the moon there are cases of collapse. There are many sages empowered with the influence of austerity and many yogis, philosophers and renouncers who sometimes exhibit their acquired power under the influence of the Rudra principle of anger and passion. The great yogi Durvasa, under the influence of this Rudra principle, picked a quarrel with Maharaja Ambarisa, and a brahmana boy exhibited the Rudra principle by cursing the great King Pariksit. When the Rudra principle is exhibited by persons who are not engaged in the devotional service of the Supreme Personality of Godhead, the angry person falls down from the peak of his improved position.
Places of Rudra
the heart, the senses, the air of life, the sky, the air, the fire, the water, the earth, the sun, the moon and austerity