Mudras are energetic seals or gestures done with the body to regulate and direct prana through our body-mind and auric field.
Here's a quick tutorial on how to do Migri or Vishnu's Mudra.
Migri Mudra for Alternate Nostril Pranayama
Nadi Shodhana (Alternate Nostril Breathing)
*Traditionally only the right hand is used for this Mudra.
It is also called Vishnu Mudra. See instructions below.
*The action of this mudra pacifies Vata, as the index finger represents Vayu (air) and the middle finger represents Akasha (Ether). By folding them into the thumb mound, we are energetically suppressing Vata. By using these specific fingers to seal and open the nostrils, we control the breath (prana). Essentially we are energetically employing the elements of water, fire, and earth to hydrate, warm, and ground Vata Dosha.
Ball your right hand into a fist.
Bend and press your forefinger and middle fingers firmly into the mound of your thumb. Stretch out the ring and pinky fingers. Keep your pinky as straight as possible, curl your ring finger slightly to press its pad to the pinky’s nail. Merge the two fingers into one by aligning the fingertips as best you can.
Turn your palm to your nose. Keep the chin directly above the sternum, the head should stay in a neutral, upright position. Keep the shoulders even. Tuck your right elbow into your torso. The ring finger (earth) / pinky (water) pair will close the left nostril, the thumb (fire) the right nostril.
Press the nostril with the fingertips. Close your right nostril and inhale slowly through your left. Then close the left, and open to exhale through the right. Finally inhale through the right, seal it, and open and exhale through the left.
Repeat for one to three minutes
Release the breath..