The Atmosphere Why is there weather? The Sun heats the surface of the Earth unequally The Earth rotates The atmosphere contains water vapour

Unequal heating is caused by the Earth’s shape Equatorial latitudes receive more energy than Polar, and are thus warmer The Earth’s atmosphere attempts to equalize the temperature around the globe by carrying warm air north and cold air south, and mixing them together This is how temperatures would look if there were no continents or oceans

Seasons & heating (p. 508) the Earth’s tilt changes the amount of sunshine received through the seasons in June the northern hemisphere is tipped toward the sun, in December, away from the sun The Earth’s rotation is elliptical (unlike this picture) so we are closest to the sun in December

The Atmosphere The atmosphere is a blanket of air and moisture that surrounds the Earth 78% Nitrogen 21% Oxygen 1% Other gases Altitude is the distance above sea level

Troposphere Closest to the surface Up to 16 km at the equator and 8 km at the poles Most of the moisture of the atmosphere is in this layer Responsible for most of the weather systems As you go further away from the earth (increase in altitude), this layer gets colder

Tropopause Thin boundary where the troposphere ends No longer a decrease in temperature as the altitude increases More ozone here to absorb UV radiation so the temperature increases The heat created by the radiation helps to keep the troposphere separate from the stratosphere

Stratosphere This layer is very dry Here there is a higher concentration of ozone than any other layer Because of the high concentration of ozone, this layer does the most to protect the earth from radiation As the altitude increases in this layer, the temperature also increases

Mesosphere The temperature and density of the gases here are extremely low Except for water vapour concentration and ozone, the composition of the atmosphere up to and including this layer are very similar Shooting stars burn in this layer

Thermosphere Low density but high energy molecules produce high temperatures High energy waves from the sun are absorbed here Also called the inosphere because radiation causes particles to become electrically charged Ions The ions produce beautiful lights called auroras (Northern/Southern Lights)

Exosphere Thin, outermost layer It can be considered space because there are so few particles present here (not very dense).

Pressure Higher altitude is harder to breathe: Air is less dense Fewer Oxygen molecules Valleys have higher pressure because there is more weight on top of it The temperature is usually higher so the air is less dense

Layers of the Atmosphere The atmosphere is thicker above the equator because the air is warmer so it expands