Why does the type of ice on a wind turbine matter to a condition assessment?

The short answer

The type and distribution of ice help describe how the event developed and which surfaces may be affected. Rime, glaze and adhering wet snow do not necessarily have the same appearance or accumulation process. These observations inform a qualified icing assessment; they do not establish a safe operating limit or a permitted approach to the turbine.

Describe the ice without overclassifying it

Rime is generally associated with freezing supercooled droplets and an opaque deposit, whereas glaze can appear smoother or clearer. Mixed conditions occur, and a distant image may not resolve the type reliably. Use the meteorological description as an observed or provisional classification. Do not translate colour into an assumed density, mass or adhesion strength, because those quantities cannot be established from a photograph alone.

Connect the observation to affected surfaces

Compare whether ice is concentrated on exposed edges, distributed unevenly across blades or visible on nearby stationary objects. Different shapes and orientations can collect ice differently. Weather at ground level may not represent the rotor region. DNV treats icing conditions, loads and detection as related but separate assessment topics; a visual type label does not demonstrate what the machine experienced or what its protection detected.

A deposit's observed form may change during an event, so a later photograph need not describe the initial accumulation. Distinguish the time of the image from the period it is being used to explain, particularly when interpreting a possible change in turbine behaviour.

Choose the next assessment question

Ask whether the available evidence can establish the extent of icing and whether hidden or poorly visible regions remain unresolved. The responsible operator must use the applicable icing and restart instructions; this page supplies no ice-removal technique or numerical exclusion distance. MARSTON ice detection, blade heating and cold-climate qualification are not assumed. The value of classification is a clearer investigation, not permission to continue or resume operation.