Why is it warm all year round in the Hawaiian Islands?
There are many reasons for Maui’s famous warm weather, not the least of which is the southern latitude. Maui is approximately 1400 miles north of the equator, which is in an area on the planet that has high sun during the entire year. This allows plentiful amounts of sunshine to beam down on the island. While the sun’s warmth heats the island, it is also pumping heat into the surrounding ocean water as well. The temperature of the ocean around Maui fluctuates very little…remaining between 75 degrees F. (23.3C) during the winter months, up to 83 degrees F. (28.3C) or so during the summer months. This last point is really the key factor in why we stay so pleasant here even during the winter. The warm ocean keeps the overlying atmosphere from cooling significantly…ensuring the near perfect weather conditions that Maui enjoys.
What are trade winds, why do they blow in Hawaii and how did they get their name?
The earth’s climate system works to constantly balance our planet’s temperatures by using a series of rotating air cells to circulate air from the warm equatorial regions towards the poles and back again. In the case of Hawaii, warm air rises near the equator to the south of the islands and moves northward through the upper atmosphere. This airflow sinks back to the earth’s surface at 30 degrees north latitude and flows back over the islands towards the equator, creating a wind moving along the ocean’s surface.
As this air streams back down from the north towards the equator, its movement is curved by the earth’s rotation, causing it to flow out of the northeast. This northeasterly wind is the famous trade winds felt in Hawaii and other tropical locations.
These circulating air cells are at work around the globe, creating trade winds within this same band of latitude both above and below the equator.
Here in Hawaii the trade winds are felt 83-95% of the time in the summer and 42-60% of the time in the winter. The consistency of these winds were well known to the early maritime traders, who traveled the world’s oceans in the days of wooden sailing ships, and they used them to cross the grea t oceans and reach distance lands to trade their goods. The wind gets its name then from these traders.
Why is it cold at the top of Haleakala volcano, and the Big Island summits, despite it’s tropical location?
The reason why temperatures on Haleakala (and all mountains here in the islands) are colder as you rise up their flanks has to do with air density and air pressure. Our atmosphere is made up of various types of gas molecules and like everything else on the planet, these molecules are drawn downward by the earth’s gravity. For this reason the atmosphere lays on our planet like a blanket with most of that atmosphere concentrated within the first few thousand feet of sea level. It then thins out as you rise in altitude.
Although we hardly notice it, the weight of all this atmosphere overhead creates air pressure and it is this air pressure which creates the difference between sea level and mountaintop temperatures.
The key principal at work here is that by its nature, air under higher pressure will hold more heat than air at lower pressures. We can all think of many examples where we’ve seen this principal at work, such as when we take the cover off a pot of boiling water and we see the water releasing some of it’s heat in the form of a cloud of steam as the pressure that had built up under the lid is released.
The higher we rise up through the atmosphere, such as when we climb up the slopes of the Haleakala, or the mountains on the Big Island, the less atmosphere there is above us, so there is less atmospheric pressure at higher altitudes and consequently lower temperatures. The degree to which the air is cooled at higher elevations depends a lot on how much moisture it is carrying, but in general, the temperatures decline approximately 3.5 degrees (F) for every thousand foot increase in altitude.
What Time of Year Do The Humpback Whales Arrive?The whales generally begin arriving in late November and most are gone by the beginning of April. The number of whales are at their peak in the months of January through March. During March the adolescent whales begin migrating back to Alaska, followed several weeks later by the non-mating adults. The last humpbacks to leave are the females with calves, these depart in March and April.