Question 53 TV02 - Towing Vessels - Great Lakes and Inland

The Correct Answer is B **Explanation for B (Bluish):** Multi-year ice (MYI) is sea ice that has survived at least one summer melt season. During the melting process, the surface snow and brine are flushed out, making the ice denser and the internal structure more pure (less trapped air, fewer impurities). When light penetrates this dense, pure ice, it preferentially scatters blue wavelengths, causing the surface to take on a noticeable bluish or sometimes greenish-blue hue. This distinct color is a key visual identifier distinguishing MYI from newer or first-year ice. **Why other options are incorrect:** * **A) Grey-white:** This color is typically associated with first-year ice (FYI), especially when it is young, covered in snow, or undergoing initial stages of freezing/brining. While multi-year ice can look white in certain lighting or if covered by fresh snow, the defining visual characteristic of the exposed, consolidated ice is not merely grey-white. * **C) Greenish:** While very old or extremely dense ice can sometimes exhibit a greenish tint (often related to trapped biological matter or specific light interactions), the most common and standard descriptor for the color of hard, thick multi-year ice due to light scattering in dense ice is blue or bluish. Greenish is less characteristic than bluish for identifying typical multi-year ice. * **D) Grey:** Grey usually describes very thin, new ice (e.g., grey ice, grey-white ice) or ice that is dirty or wet. Multi-year ice is generally much thicker and visually characterized by its color resulting from density and purity, which presents as blue.