Insolation and Temperature Flashcards
What are the factors that affect temperature?
Latitude, albedo, cloud cover, ocean currents, unequal heating of land and sea and altitude.
Which of the factors that affect temperature affect insolation first?
Latitude and albedo.
How does latitude affect insolation?
Latitude affects insolation for two reasons, beam spreading and atmospheric beam depletion as well as seasonal variation.
What is angle of incidence?
Angle of incidence is the angle at which sun’s rays strike the Earth’s surface.
What is beam spreading?
Beam spreading is the increase in surface area over which radiation is distributed in response to a decrease in angle of incidence.
How does beam spreading affect insolation (and in turn temperature)?
The closer the latitude is to the equator, the greater the angle of incidence and the lesser the degree of beam spreading which leads to more intense radiation because the beam is concentrated to a small area (which leads to higher surface temperatures).
How does atmospheric beam depletion affect insolation (and in turn temperature)?
The closer the latitude is to the equator, the smaller the thickness of atmosphere the sun’s rays have to penetrate before they reach the Earth’s surface. The beam is hence not weakened much because not much of its radiation is reflected back into space - most of it is absorbed. This contributes to higher insolation receipts (and hence higher temperature).
Why does insolation vary based on the time of the year?
The Earth is tilted at about 23.5° angle at its axis as it revolves around the sun. For half the year, the Northern Hemisphere is oriented somewhat towards the sun and for the other half of the year, it is directed away from the sun. Same applies to Southern Hemisphere. This causes the position of the overhead sun to change too.
What’s it like during the June Solstice?
The Northern Hemisphere is tilted towards the sun and the sun is overhead at the Tropic of Cancer. During this period, the Northern Hemisphere is experiencing summer and the Southern Hemisphere is experiencing winter because every latitude in the Northern Hemisphere is receiving more insolation than its corresponding latitude in the Southern Hemisphere. This is due to the generally higher angles of incidence and longer periods of daylight in the Northern Hemisphere.
What’s it like during the December Solstice?
The Southern Hemisphere is tilted towards the sun and the sun is overhead at the Tropic of Capricorn. During this period, the Southern Hemisphere is experiencing summer and the Northern Hemisphere is experiencing winter because every latitude in the Southern Hemisphere is receiving more insolation than its corresponding latitude in the Northern Hemisphere. This is generally due to the higher angles of incidence as well as the longer periods of daylight in the Southern Hemisphere.
What about the equator?
At the equator, there is very little variation in the amount of insolation received as the length of day and angles of incidence do not change very significantly throughout the year. During both solstices, the equator receives 12 hours of daylight. It also receives 12 hours of daylight during the equinoxes.
What’s the difference between latitude and albedo as factors of insolation?
The scale. Albedo affects insolation on a smaller scale.
What is albedo?
Albedo is a measure of the reflectivity of the Earth’s surface. Albedo is generally low in the tropics due to dark, dense forests (especially in areas with tropical rainforests which have only 7-15% reflectivity).
What are the anomalies in albedo?
North Africa has higher average albedo due to reflective nature of surfaces in this area such as sand, in Sahara Desert.
What affects albedo other than surfaces?
Clouds. Cumulonimbus clouds that are about 1000m thick reflect back 90% of the light that falls on them. Clear skies in low-latitude deserts explain why day time temperatures are so high it can reach 50℃.
What is albedo like in the poles?
There is an energy deficit at the poles which is explained partly by albedo because the surface there is dominated by ice and snow which have about 80-90% reflectivity.
How does cloud cover affect temperature without affecting insolation?
Longwave radiation. The thicker the cloud cover, the greater the amount of longwave radiation that is reflected back towards the surface. This explains why night-time temperatures in low-latitude deserts can fall even below 0℃ because the lack of cloud cover means that almost all of the longwave radiation can escape back into space at night, resulting in low temperatures.
How do ocean currents affect temperature?
Where the water temperatures are high, heat is transferred to the atmosphere that promotes higher air temperatures. Thus, the existence of cold offshore currents can cause a location to have lower temperatures.
What is an example of ocean currents affecting temperature?
The Humboldt (Peruvian) current is a cold ocean current that flows in the north-west direction along the west coast of South America. This cold ocean current results in cooler waters in the Eastern Pacific.
What are all the hot ocean currents?
North Pacific Drift, Brazillian, Mozambique, East Australian, around India, Kuroshio.
Why do water bodies take longer to warm and cool compared to land surfaces?
Water has a higher specific heat capacity, radiation received at the surface of a water body can penetrate through several tens of meters deep, the warming of a water surface can be reduced considerably due to a vast supply of water available for evaporation and water can be mixed both horizontally and vertically.
How does having a higher specific heat capacity allow water to warm slower than land?
Due to having a higher specific heat capacity, greater amounts of energy are needed to raise the temperature of water in comparison to land masses.
How does more penetration allow water to heat up slower than land?
Because radiation received at the surface of a water body can penetrate through several tens of meters deep, energy can be distributed through a large mass. In contrast, insolation absorbed by land heats only a very thin, opaque surface layer.
How does evaporation reduce warming of a water surface considerably?
Much energy is used in the evaporation process because a vast amount of water is available for evaporation and so less warming occurs from less heat energy.
How does the mixing of water both vertically and horizontally lower temperature?
Energy surpluses from one area flow to regions of lower temperature and due to energy distribution, heat is gained slower unlike land.
How does unequal heating of land affect temperatures?
Due to unequal heating of land and water, there is generally smaller surface temperature changes over oceans as compared to continental interiors.
How does altitude affect temperatures?
Mountainous areas within the tropics have cooler temperatures than places at similar latitudes nearer sea level. Temperatures generally decrease as altitude increases as the thinning of atmosphere with increase in altitude reduces its ability to absorb and emit longwave radiation.
An example of altitude affecting temperature?
The cities of Concepción and La Paz in Bolivia are both located at 16°S. However, the hot and humid climate of Concepción, at much lower elevation (490m above sea level) stands in marked contrast to the cooler climate of highland La Paz. Average annual temperature in Concepión is about 23°C while La Paz averages at about 11°C.
