Tilt of Earth

CONTENT | REFERENCES | RESOURCES | SPONSORS | CONTRIBUTORS | HOW TO USE THIS CD
CLIMATE CHANGE IN CONTEXT PREVIOUS | NEXT

3.2.1.a  Tilt of Earth

 

 

Heat energy is also reflected back into the atmosphere as light. This reflectivity is called albedo. If there is a high albedo, there is high reflectivity of light and only a small amount is absorbed. The temperature is cooler. Light, shiny, and smooth surfaces have a higher albedo than dark, dull, and rough surfaces. For example, snow-covered fields reflect more light than a deciduous forests. Albedo is the proportion of the sun’s energy reflected by the Earth. Here are the albedo proportions:

Snow 0.9
Bare land 0.3
Sea water 0.1

Earth’s energy should be in balance. That is, energy absorbed from the sun should equal the energy emitted by the Earth at steady state. The mathematical model for this is:
p R2 Es (1 – a) = 4 p R2 (f s T4)
where
p (pi) = 3.14…
R = radius of the Earth
Es = Energy emitted by the Sun
a = albedo
f = greenhouse effect
s = Stefan-Boltzman constant
T = surface temperature of the Earth

When albedo is high, more energy is reflected and the left side of the equation has a smaller value. In ice-albedo feedback, more cooling will increase the amount of snow and ice, which increases overall albedo, which decreases energy absorbed from the sun, which increases cooling, which increases the amount of snow and ice, and so on. Runaway ice-albedo may occur if ice extends below 30o N and S latitudes.

Canada’s climate is affected by these factors of latitude. Mainland Canada lies in the middle latitudes between approximately the 49o and the 70o latitudes of the North Hemisphere. Mainland Canada experiences seasonal changes in temperature, precipitation, winds, and cloud cover. Places in Ontario closer to the 70o latitude where ice and snow accumulate have much cooler temperatures than those closer to the 49o latitude.

Leave a Reply