Monthly Archives: June 2013

The Hawaiian climate

The Köppen climate classification defines a number of different climate types.

Group A (Tropical Humid)

  • Tropical Rainforest
  • Tropical Monsoon
  • Tropical Wet and Dry / Savanna

Group B (Dry)

  • Steppe
  • Desert

Group C (Mild Mid-Latitude)

  • Dry-Summer Subtropical / Mediterranean
  • Humid Subtropical
  • Maritime Temperate / Oceanic
  • Temperate Highland Tropical with Dry Winters
  • Maritime subarctic / Subpolar Oceanic

Group D (Severe Mid-Latitude)

  • Hot Summer Continental
  • Warm Summer Continental / Hemiboreal
  • Continental Subarctic / Boreal / Taiga

Group E (Polar)

  • Tundra
  • Ice Cap


A map of the world coloured using the extended Köppen-Geiger scheme which features twenty-nine climate types.

Hawai’i, the largest of the Hawaiian islands, features ten of the thirteen Köppen Climate Types.

At the summits of Mauna Kea and Mauna Loa the climate type is Polar Tundra. Below the summits of the Hawaiian mountains are narrow bands of Continental Subarctic climate, and below that a region of Warm Summer Continental climate. The largest area of Hawai’i is covered by Hot Summer Continental climate.

Moving towards the coast there are regions of Tropical Rainforest, Tropical Wet and Dry, Humid Subtropical and even a tiny region of Tropical Monsoon climate. Towards the north-east of Hawai’i there are even small regions of Steppe and Desert climate.


A false-colour image of Hawai’i showing the different types of land use.

Sacrificial anodes

Salt is a catalyst for the rusting process and therefore rusting is a major hazard for boats, ships and installations like oil rigs and offshore wind turbines.

Aside from painting with anti-rusting paint, one of the major methods of preventing rusting is the use of sacrificial anodes.


Sacrificial anodes for sale in the window of the Fishermen’s Mutual Association shop in Pittenweem.

Sacrificial anodes are made of a material more reactive* than the material they are designed to protect. This creates a difference in electrical potential that is in the opposite direction to what would normally be the case, and the sacrificial anode is eaten away instead of the material being protected.


A ship’s hull with mounted sacrificial anodes.

Sacrificial anodes are usually made from magnesium, zinc or aluminium; magnesium is used on-shore and in freshwater, and zinc and aluminium are used in salt water where resistance is lower.

* Technically they have a more negative electrochemical potential.