Wednesday, September 17, 2008

Viewing distant islands--O'ahu from Kaua'i

I looked out across the ocean east of Kaua'i yesterday, and saw O'ahu.

It sat there on the horizon, a dark hump in the distance, with a low shelf off to the right side. Not clear enough to pick out gullies from ridges, but clear enough to know it was real.

(This is the scene yesterday morning looking toward O'ahu from Nawiliwili on Kaua'i. With the naked eye, the shape of the island was visible, but the camera was unable to resolve the island's outline.)

This isn't unheard of. Kaua'i residents who live in Kalaheo and Wailua Homesteads report that on special days, they sometimes spot the island from their highland vantages.

And other folks say they'll spot it from time to time even from Lihu'e.

But being able to see O'ahu from Kaua'i or vice-versa is rare.

I've never seen a photo of one island taken from the other, and even on this day, it was still hazy enough that while my eye could pick the shape of the island out, my camera could not.

O'ahu folks know how hazy Moloka'i can be in the distance, across the Kaiwi Channel. Well, the Ka'ie'iewaho Channel more than twice as wide as the Kaiwi. Sixty miles from closest point to closest point.

On a normal day, there's nothing at all sitting on the horizon.

I'm assuming the island was visible because the air was unusually clear. There had been a couple of days of calm, which let the ocean spray settle down. And the trades had just returned, lightly, to push the vog away.

As the wind picked up on the ocean, the island grew more faint, and by midday it was gone again.
I have sailed between the islands, and normally have been able to pick Kaua'i out on a voyage from O'ahu at a range of 40 miles to about mid-channel, depending on ocean conditions.

For those cogitating on the issue, viewing these islands does not require any special bending of light. The highest point on the Wai'anae range is near 4,000 feet and Kaua'i is more than 5,000 feet high.

Even from sea level, the curvature of the Earth would obscure the bottom half of the view, but leave a significant piece of the island visible.

Smaller islands are often close enough to be viewed before they actually rise above the horizon.

From a sailing vessel, the island of Nihoa, west of Kaua'i, first appears as a pair of nubs above the horizon—the tops of its twin peaks. Then, as you sail closer, the saddle between them rises. And still closer, the island rises to look like a giant molar, with vertical sides, peaks on both extremities, and the saddle between.

© 2008 Jan W. TenBruggencate

1 comment:

Andrew Cooper said...

It is a rare day we have much visibility between islands, even worse when the vog obscures the view. Every few weeks I get a glimpse of Kaho'olawe from the Kona coast at a distance of 60 miles. Seeing Maui is possible most days, since Haleakala rises above the haze that obscures the view closer to sea level.

One day last month was exceptionally clear, from the summit of Mauna Kea I could see Maui, Kaho'olawe, Lanai and just a glimpse of Oahu in the far distance.