LOCATION: Prince William Sound straddles the 60th parallel and is farther north than Cape Horn is south. Within its 10,000 square miles and 3,000 miles of heavily convoluted coastline. To the south, Montague Island serves as a fifty mile long breakwater protecting the sound from the often tempestuous Gulf of Alaska. To the west, north, and east, the high peaks and vast icefields of the Kenai and Chugach mountains create an effective barrier geographically isolating the sound from adjacent areas. . . .
CLIMATE: The sound has a maritime climate with moderate temperatures and copious precipitation. To the south, Kodiak Island experiences a warmer oceanic climate while to the north interior Alaska has a continental type of climate typified by direr weather and extreme temperature ranges. Although precipitation may fall as rain most of the year at sea level, the moist warm air soon cools as it rises over the steep mountains where it drops prodigious amounts of snow - 400 to 800 inches annually.
Because of its varied terrain, the sound has many microclimates - regions where the climate differs significantly from adjacent areas. For example, often on a clearing day following a period of inclement weather, rain continues to fall over forested hillsides while the area around a glacier is light and sunny. Rainfall persists over the forested areas because moisture evaporating from warm, vegetated land rises, cools and releases precipitation again. Meanwhile, the glaciers lose much less water to evaporation and reflect light (albedo effect). Consequently, the clouds are fewer and appear lighter over a glacier. Sailors are familiar with another microclimatic condition associated with glaciers. Because of their colder temperatures, local high pressure systems form over the glaciers while the adjacent sound, with its warmer water, tends to have a lower pressure over it. The difference in pressure causes air to move from the area of higher pressure to that of lower pressure creating local glacier breezes.
Early explorers, whose brief visits coincided with gales, described the sound as wet, cold, foggy and generally inhospitable. Those who saw the sound in sunshine found it an unforgettable land whose chief resource was its unparalleled scenic quality. John Muir was one of the latter:
But just as we entered the famous Prince William Sound, that I had so long hoped to see, the sky cleared, disclosing to the westward one of the richest, most glorious mountain landscapes I ever beheld - peak over peak dipping deep in the sky, a thousand of them, icy and shining, rising higher, higher, beyond and yet beyond one another, burning bright in the afternoon light, purple cloud-bars above them, purple shadows in the hollows, and great breadths of sun-spangled, ice-dotted waters in front. The nightless days circled away while we gazed and studied, sailing among the islands, exploring the long fiords, climbing moraines and glaciers and hills clad in blooming heather - grandeur and beauty in a thousand forms awaiting us at every turn in this bright and spacious wonderland. But that first broad, far-reaching view in celestial light was the best of all. (Muir 1901, I:132).
Today, what astounds many people most about the sound is the presence of so many glaciers at sea level where the temperatures are obviously above freezing during the summer and for much of the winter as well. Their first thought is often - why don't the glaciers just melt? In general, the answer, of course, is that the glacial ice is melting, but as fast as it melts, new ice flows down the mountainside to replace it.
PRINCE WILLIAM SOUND'S GLACIERS: Prince William Sound is noted for its surrounding icefields from which flow numerous glaciers that often reach sea level. Contrary to popular misconceptions, the sound does not contain its innumerable glaciers just because of cold temperatures. Winter temperatures in interior Alaska, where there are fewer glaciers, are much colder. Instead, so much snow falls during the winter months on the Chugach and Kenai mountains that it cannot all melt during the summer. Gradually, glaciers form and begin to move under the force of gravity toward the sea.
Prince William Sound's glaciers are classic examples of temperate glaciers. Unlike polar glaciers, such as those found in Greenland and Antarctica, which are below freezing and static, temperate glaciers are at or near the freezing point during most of the year and slide over their bedrock. Because snow recrystallizes into ice much faster when it thaws and refreezes repeatedly, the time it takes snow to become glacial ice is much shorter on a temperate glacier than on a polar one.
The Prince William Sound region, with seventeen tidewater (calving) glaciers, is unique in having so many glaciers terminating at sea level. Topography plays an important role in the large number of tidewater glaciers. For many of these, the descent from the accumulation areas to tideline is extremely abrupt.
Until recently, all but one of the tidewater glaciers has undergone a major retreat within the last few centuries. Some, like Columbia, Nellie Juan, Yale and Shoup, are in the drastic retreat phase of their cycle. Other formerly tidewater glaciers now terminate on land, such as Falling and Taylor glaciers. Nine tidewater glaciers are now slowly advancing: Blackstone, Harriman, Surprise, Cascade, Coxe, Bryn Mawr, Wellseley, Harvard and Meares. . . .
(Chapter 1, pp. 1-5).