A turbine comprising: a seal ring including an inner surface having a track for a turbine blade defined therein and a target surface positioned opposite the inner surface of the seal ring, a carrier positioned radially outward from the seal ring, the carrier having an annular rib that extends from an annular wall of the carrier radially inward to an inner surface that faces, but is spaced apart from, the target surface of the seal ring, the annular rib further including an impingement hole that extends through an outer surface of the carrier and the inner surface being positioned opposite the outer surface, the inner surface of the carrier being spaced apart from and facing the target surface of the seal ring, and a source of positive pressure to move air through the impingement hole into contact with the target surface of the seal ring, wherein the impingement hole includes (i) an outer opening defined in the outer surface and a first inner wall extending inwardly from the outer opening to define a first passageway having a first diameter, and (ii) an inner opening defined in the inner surface and a second inner wall extending inwardly from the inner opening to define a second passageway that is connected to the first passageway and has a second diameter that is greater than the first diameter, wherein the second passageway has a longitudinal axis, and an imaginary line extends along the longitudinal axis and has a line length that is defined between the inner opening of the carrier and the target surface, the line length being defined by the following equation: 1.0 < Z D 2 < 4.8 where z is the line length and D 2 is the second diameter. a seal ring including an inner surface having a track for a turbine blade defined therein and a target surface positioned opposite the inner surface of the seal ring, a carrier positioned radially outward from the seal ring, the carrier having an annular rib that extends from an annular wall of the carrier radially inward to an inner surface that faces, but is spaced apart from, the target surface of the seal ring, the annular rib further including an impingement hole that extends through an outer surface of the carrier and the inner surface being positioned opposite the outer surface, the inner surface of the carrier being spaced apart from and facing the target surface of the seal ring, and a source of positive pressure to move air through the impingement hole into contact with the target surface of the seal ring, wherein the impingement hole includes (i) an outer opening defined in the outer surface and a first inner wall extending inwardly from the outer opening to define a first passageway having a first diameter, and (ii) an inner opening defined in the inner surface and a second inner wall extending inwardly from the inner opening to define a second passageway that is connected to the first passageway and has a second diameter that is greater than the first diameter, wherein the second passageway has a longitudinal axis, and an imaginary line extends along the longitudinal axis and has a line length that is defined between the inner opening of the carrier and the target surface, the line length being defined by the following equation: 1.0 < Z D 2 < 4.8 where z is the line length and D 2 is the second diameter.