What influences temperatures?

Hot summer day in Hanko, the southernmost tip of Finland
On hot summer days sea surface temperatures are usually lower than temperatures in the air above ground. Photo: Foreca, Hanko, Finland

Temperature differences on Earth are primarily influenced by uneven distribution of solar radiation. Also seas, mountain ranges and clouds influence temperatures.

Temperatures, as well as annual rainfall patterns, define climate regions. There are many factors that influence temperatures: proximity to water bodies, ocean currents, orography, air masses, distribution of solar radiation, humidity, rainfall, wind and cloudiness. Uneven distribution of solar radiation on Earth is the main factor in defining annual temperature changes in a region.

Oceans keep temperature fluctuations in check

Oceans and other sizeable water bodies store thermal energy and damp both daily and annual temperature fluctuations. Temperatures in areas surrounded by sea water, for example in Maledives, quite closely follow sea surface temperatures. 

Ocean currents affect local climate by transporting heat to the region. The Gulf Stream is a good example of this, as it transports warm water from the Gulf of Mexico all the way to the Arctic Ocean. Because of this northern Europe is on average several degrees warmer than other areas in same latitudes especially in winter months.

Cold on mountain tops, warm in valleys

Mountains and mountain ranges can affect temperatures in different ways. When climbing up a mountainside, temperatures drop on average 10–12 degrees Fahrenheit (6–7 degrees Celsius) per 0,62 miles (one kilometer). Because of this most mountaintops in the tropics are covered by snow and ice.

Mountains often trigger local winds, such as the foehn wind. It is a warm wind that flows down slopes. Temperatures in foehn-affected areas can be significantly higher than those on the other side of the mountain.

At cloud level on the Madeiran mountains it is usually significantly cooler than lower on the beaches. 
At cloud level on the Madeiran mountains it is usually significantly cooler than lower on the beaches.  Photo: Foreca, Madeira

Clouds protect from solar radiation and prevent heat from escaping Earth

Grey skies in Keilaniemi, Espoo
In mid-latitudes in wintertime low clouds and fog prevent heat from escaping from the ground into space. Without the clouds temperatures would be colder. Photo: Foreca, Keilaniemi, Espoo, Finland

Clouds dampen daily temperature fluctuations. They prevent daytime temperatures from rising as high as they might in clear weather, and nighttime temperatures from falling as low as they would without clouds. 

Higher up in the atmosphere upper-level clouds warm up the weather: they let solar radiation reach the ground, but stop long wave heat radiation from the ground from escaping into space. Mid- and low-level clouds cool the weather, as much less solar radiation is able to pass through them.

Air masses also affect temperatures

Meteorologists often talk about air masses, large areas of air with qualities that vary only a little. As meteorologists talk about air mass temperatures, they refer to the temperature at the level of roughly 4,500 feet. At this level temperatures aren't much affected by whether it is day or night. Air masses such as arctic, polar, midlatitude and tropical air mass form belt-like circles around the globe.

At the edges between two air masses winds tend to increase especially higher up in the atmosphere. Low pressure areas, that sometimes even become storms, travel along these edge regions.

In these edge region areas, which can be hundreds of miles wide, temperatures may rise or fall greatly within just hours, as a cold air mass is replaced by a warm one or vice versa. This is typical for midlatitude areas, whereas in the tropics similar fluctuations don't happen.'

Wind mixes the air and evens out temperature differences.
Wind mixes the air and evens out temperature differences. Photo: Foreca, Sauvo, Finland

Winds dampen temperature fluctuations

Winds dampen temperature fluctuations by mixing air in vertical columns. Very cold temperatures in higher latitudes can only occur in clear weather with practically nonexistent winds; in these conditions heat radiation can escape the Earth into space.

Sea breeze is a wind phenomena that can cool down temperatures close to coastlines. 

Article last updated 2/25/2021, 8:20:00 AM

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