Lesson 76: Atmosphere, Weather, and Climate
In this lesson, we will learn about the layers of the atmosphere, air currents,
and the different factors that combine to make up a region's climate.
The atmosphere is a collection of gases that gravity holds in
a thin envelope around the Earth. The atmosphere consists of four layers - the
troposphere, stratosphere, mesosphere and thermosphere.
The Troposphere is the lowest layer of atmosphere. It moderates temperatures
and is where air shifts from cooling to warming up. All weather and climate
occur in the Troposphere.
The Stratosphere is the layer above the troposphere, and
is where temperature increases with altitude.
The Mesosphere and thermosphere are layers above the stratosphere where ozone
decreases and only a small amount of oxygen and nitrogen are present.
Climate is affected by the movement of air. Lighter air rises causing vertical
air currents. These currents create convection currents. As air flows in to
replace warm air that is rising, the inflow leads to horizontal airflows or wind.
Convection currents bring day to day weather changes.
Jet streams are rivers of air that
flow eastward at speeds of more than 300 mph and move around a lot.
Fronts are boundaries where air masses of different temperatures and
pressures meet.
Monsoons occur when there is a major difference between oceans and continents
in cooling and heating. Monsoons in the Indian subcontinent are famous for
rains and also for devastating floods when there is too much rain.
Air patterns, precipitation, wind, and
the movement of the Earth on its axis creating seasons,
all contribute to a region's climate.