The Reasons for the Seasons

A pre-lab experience…

Climate or weather?

• Climate is…– A measurement of long term

events that occur in a region during a long period of time.

– Climate is described with the same measurements as weather, but these measures are averaged over years, decades and/or centuries.

• Weather is…– A measurement of short term

events that occur in a specific place and during a specific and narrow period of time.

– It is the current state of the atmosphere.

– Weather occurs only in the Troposphere

– Measurements of weather include the following:

• Temperature• Precipitation• Humidity• Wind speed• Visibility/Cloudiness

Colorado Climateand

Solar Radiance Energy from the Sun is organized in the EMS.

Temperature on Earth results largely from the visible light portion of the spectrum

Colorado Climateand

Solar Radiance• The climate of Colorado is influenced by elevation.• The average elevation in Colorado is approximately

6,800’ (which is the highest average elevation of any state/province in North America!)

• Because of the high elevation, there is less atmosphere between us and the Sun!

• As elevation increases, the amount of solar radiance received increases.

Colorado Climate

• As elevation increases, the thickness of the atmosphere decreases.

• As the thickness of the atmosphere decreases, the amount of solar radiance (light) that reaches the surface of the Earth increases.

• As the amount of light reaching the surface of the Earth increases, the amount of light absorbed increases.

• As the amount of light being absorbed increases, the temperature of the absorbing body increases.

How does the Sun influence weather?

• Nature demands EQUILIBRIUM!• Different sections of the Earth receive different

amounts of Solar Radiance.– Tropics receive more Solar Radiance.– Amount of Solar Radiance decreases with increased

latitude.

• Weather is the result of the Earth re-distributing the energy it receives from the Sun!

• This is how Nature tries to create Equilibrium!