Transcript Weather Powerpoint 2

What Causes Weather?
We should have discovered that
land and water do not heat up at
the same rate. If things went
correctly, we should know that
land heats up & cools down
faster than water. Therefore, the
sun will heat up land quicker than
oceans.
That means that the hot air over
land rises and cool air from over
the ocean will blow in to take its
place.
This uneven heating of the Earth
causes hot air to rise and cold air
to sink, leading to movement of
air in the atmosphere.
atmosphere
• A blanket of air surrounding the Earth
• made up of gases, water, dust, & other small
particles
• It is divided into layers, based on
temperature
• troposphere, stratosphere, mesosphere,
thermosphere
Troposphere
• Bottom layer of the
atmosphere
• most of Earth’s
weather occurs here
• 8 miles thick (13 km)
• Supersonic aircraft fly
in this layer
Stratosphere
• 2nd layer of the
atmosphere
• contains the ozone
layer
• some aircraft fly in
this layer
• 21 miles (50 km)
Mesosphere
• Third layer of the
atmosphere
• coldest layer
• this is the layer where
meteors burn up
• 50 miles (80 km)
Thermosphere
• The top layer of the
atmosphere
• very high temperatures
• gradually merges into
space
• 196 miles (320 km)
Air pressure
• Gravity pulls on air
• lower in the atmosphere means greater air
pressure
• cold air is heavier than warm air
• when cold air sinks it forces up warm air
Wind
• Movement of air
• air is constantly
moving
• 3 reasons
• gravity, temperature,
Earth’s rotation
• moves from high to
low or cold to warm
Local Wind
• A wind that results
from a local difference
in temperature
• wind blowing in from
the sea over a beach
during the day
• wind blowing from
land to water at night
Prevailing winds
• Global winds
• always blow in the
same direction
• caused by uneven
heating of the Earth’s
surface and rotation
• creates many circles of
air
• moves in curved paths
????????
• What two factors cause prevailing winds?
• In what layer of the atmosphere does most
weather occur?
• In what layer is the ozone layer?
• What drives all weather on the Earth?
• Why is the climate warmer near the
equator?