When talking about climate we usually refer to conditions in the atmosphere, such as temperature, rainfall, air pressure, winds, etc. However it is equally appropriate to talk about the climate in the sea and there one can discuss parameters such as temperature, salinity, currents and other factors. In fact few things have a greater impact on the climate in Iceland than the ocean currents around it.

The fact that Iceland is surrounded by ocean means that any fluctuation in temperature will be reduced as much energy is needed change it. In the small island of Grímsey that is surrounded by the sea the annual variation in temperature is considerably less than in Akureyri where the influence of the sea is less (see figure on the right).

The average temperature in the winter months is lower in Akureyri than in Grímsey but the summer months in Grímsey are considerably lower than in Akureyri. The warmest month in Akureyri is July but in Grímsey it is August. This can also be explained by the influence of the sea because the sea takes longer time to cool than the land, and generally the sea is warmest around the coast of Iceland in August.

The Marine Research Institute in Iceland has mintored the sea surface temperature in Grímsey and Hjalteyri since 1987. The measurements show results similar to the air temperature measurements in Grímsey and Akureyri. The average temperature of Hjalteyri is 0.8°C higher than the temperature during the same period in Grímsey. At Hjalteyri the minimum temperature is below that in Grimsey but the maximum temperature and the seasonal fluctuations are greater at Hjalteyri. The average temperature of the seawater in Eyjafjörður is higher than the air temperature, except during the summer months from May to August. Therefore the ocean cools the air in summer and warms it during winter. When the sea is colder than the air fog can form because the water vapour in the air condenses as it cools when in contact with the sea. Because of this fog is seldom observed during the winter but it is more common during spring and summer.

Another phenomenon known as frost smoke occurs when very cold air flows over much warmer water. Then the air warms and also becomes saturated with water vapour from the ocean but when it rises it cools again and the water vapour condenses and fog is formed and then it appears as if smoke rises from the sea.

Steingrímur Jónsson

Lofthiti á Akureyri og í Grímsey á árunum 1931-1960. Einnig er sýndur lofthiti á Akureyri á árunum 1961-1990. Meðalhiti yfir allt tímabilið er sýndur í sviga (gögn frá Veðurstofu Íslands). Lofthiti á Akureyri og í Grímsey á árunum 1931-1960. Einnig er sýndur lofthiti á Akureyri á árunum 1961-1990. Meðalhiti yfir allt tímabilið er sýndur í sviga (gögn frá Veðurstofu Íslands).

Yfirborðshiti sjávar við Hjalteyri og í Grímsey á árunum 1987-1996. Meðalhiti yfir allt tímabilið er sýndur í sviga (gögn frá Hafrannsóknastofnuninni). Yfirborðshiti sjávar við Hjalteyri og í Grímsey á árunum 1987-1996. Meðalhiti yfir allt tímabilið er sýndur í sviga (gögn frá Hafrannsóknastofnuninni).

Dagsmeðaltöl af lofthita á Akureyri og yfirborðshita sjávar við Hjalteyri á árunum 1992-1993 (gögn frá Hafrannsóknastofnuninni og Veðurstofu Íslands). Dagsmeðaltöl af lofthita á Akureyri og yfirborðshita sjávar við Hjalteyri á árunum 1992-1993 (gögn frá Hafrannsóknastofnuninni og Veðurstofu Íslands).

Mánaðarleg frávik í yfirborðshita sjávar við Hjalteyri og í Grímsey frá meðaltali áranna 1987-1996. Grænu ferhyrningarnir gefa til kynna að gögn séu ekki til (gögn frá Hafrannsóknastofnuninni). Mánaðarleg frávik í yfirborðshita sjávar við Hjalteyri og í Grímsey frá meðaltali áranna 1987-1996. Grænu ferhyrningarnir gefa til kynna að gögn séu ekki til (gögn frá Hafrannsóknastofnuninni).