Picture postcard beaches of white sand with turquoise blue water are what so many tourists imagine when Hawaiʻi is mentioned. Add a few coconut palm trees and you have the ideal beach of song and legend.
What surprises many tourists is that this postcard ideal is not the reality of our island. Black rock shorelines are the norm. Once under water you will find the sandy areas are interspersed with coral reef, the rocky shorelines usually supporting extensive coral reef rather than sand.
It is the coral that is the source of the white sand beaches here in Hawaiʻi, ground coral chewed and digested by the many coral eating fish. The pretty triggerfish and parrotfish chew the coral constantly, crushing the coral into a fine grained sand. Our pretty sandy beaches are literally fish shit.
While not exactly rare, there are quite a few, beaches where the sand continues into the water are not the rule along the Kona coastline. Most of the coastline feature black lava shorelines where the water crashes against bare rock. This rocky shoreline accounts for something like 90% or more of the coastline of the Island of Hawaii.
This stands as a stark contrast to other tropical shorelines around the world, where miles upon miles of beach are not uncommon, sand as far as the eye can see. Here on the Big Island the few truly good beaches are treasured and well used parks.
Coconuts are not the usual shoreline tree either, that role belongs to either the kiawe tree or what is locally called ironwood. Both names are not what you would find in the botanical texts. Kiawe is the island name for what the rest of the world calls mesquite or Prosopis pallida, a drought tolerant tree that covers much of the dry leeward shorelines. Likewise the local ironwood is actually the beach she-oak or Casuarina equisetifolia. The rather confusing name ‘ironwood’ is used for over thirty different species around the world.
Another surprise to many is that this island has black sand beaches. In place of ground coral these beaches are ground up lava, often created by the interaction of hot lava and cold water shattering the rock into a deep black sand. There is even a green sand beach, where the sand is in large part made up of the semi-precious gemstone olivine.
Hawaiʻi is the youngest island in the chain, the forces of erosion, coral growth, and hungry fish, have not had enough time to create the long sandy beaches. These beaches become more common as you jump northward from island to island. Oahu or Kauai have extensive beaches along a much large percentage of shoreline. The islands in the northwest Hawaiʻian islands, places like Kure and Midway are pretty much nothing but sandy beach.
We do have beaches, and they are pretty good.
When two bodies of fluid are moving in different directions interesting things happen at the boundary. The result is usually some sort of wave… Waves on the surface of the ocean or waves in the sky.
Waves on the sea surface are easy to see. Waves in the sky? Not so much. These waves are only betrayed if clouds form in the waves, revealing these structures.
This sort of wave is called a Kelvin-Helmholtz wave after Lord Kelvin and Hermann von Helmholtz who first investigated how these waves form. Yes this is the same Kelvin for whom the units of temperature are named. KH waves are visible all around us for those who know to look, from the surface of our ocean to the clouds of Jupiter, these characteristic swirling patterns are seen.
In the Saddle region over Mauna Kea and Mauna Loa, there are usually two air masses moving in different directions. Below the inversion level the tradewinds push westward. While above the inversion level, usually about 6-7,000ft, the upper air moves to the east. Where these two meet there are often KH waves, and occasionally some clouds to outline these fascinating structures.
A gorgeous image released by NASA’s Earth Observatory this week. it features the recent snowfall atop our island’s summits. I suggest you go to the link above, download the 6k x 6k version, then just zoom in and enjoy the detail! (Sorry the full image is bigger than the WordPress size limit to post here)
I does look like we will have a white Christmas here on the Big Island. Yes it snows in Hawaii, at least atop our nearly 14,000ft mountains.
It is currently snowing with freezing fog at the summit. The morning ranger report noted that there are blizzard conditions on the summit and that the road was impassable. The road is closed to all vehicles (not just the public) and the snow removal crews will not attempt to clear the road today. I am scheduled to go up tomorrow, I do have a few things I would like to get done, this may not happen.