Download Earth`s Weather and Climate

Earth’s Weather and Climate
Our Weather and Climate
• Weather
– The condition of the
atmosphere at a certain
time and place.
– Changes daily
• Climate
– The overall weather
patterns of an area
– Changes occur over long
periods of geologic time
Solar Energy
• Earth receives energy from the sun by
radiation.
• Radiation is the transfer of energy as
electromagnetic waves.
• The suns radiation enters Earth as
• Visible light
• Infrared waves - heat
• Ultraviolet radiation
Solar Energy from the Sun
Energy from the sun is transferred around Earth
by radiation and convection.
Energy
from the
sun creates
convection
currents
in the
atmosphere
and oceans
Convection Currents
• Convection is the transfer of thermal energy by
the circulation of liquids and gases.
• Warm air or water rises
– It’s less dense
• Cool air or water sinks
– It’s more dense
Ocean Currents
Warm water rises and cooler water sinks
Wind and Ocean Currents
Influence Earth’s Weather and Climate
Temperature of Our Oceans
– Ocean water cools down and warms up much slower than
land or air.
– Oceans keep temperatures for nearby
land much more moderate.
• Temperatures are less extreme
• Doesn’t get too cold or too hot
– This keeps coastal areas cooler in
the summer and warmer in the winter.
Land and Sea Breezes
• Winds caused by uneven heating of air above
ocean water and land.
• Land heats up and cools down much faster
than ocean water.
• Land gets much hotter during the day and
much cooler at night.
Coastal Areas experience Sea
Breezes during the day
• Sea Breezes
Coastal Areas also Experience
Land Breezes at Night
• Land Breezes
Sea Breezes by Day
Land Breezes by Night
Valley and Mountain Breezes
Ocean Currents
• Stream like movements of water in oceans
• Heat is transferred around the world by ocean
currents through convection.
– Over ½ the heat that reaches the Earth from the
sun is absorbed by the oceans surface.
Surface Currents
• Currents at or near the
surface of the ocean
• Caused by WINDS!
• Affect weather and climate
for coastal regions around
the world.
– Warm currents originate at the
Equator
– Cold currents originate at the
Poles
Deep Water Currents
• Deep currents far below the surface of the
ocean.
• Water is cold and salty which makes it more
dense and sinks to the ocean floor.
Currents Trade Places
• Water from deep currents get warmer as they
reach the equator and starts to rise.
• Water from surface currents get colder as they
reach the poles and starts to sink
• Heat is transferred by convection currents, in
our oceans. Warm water rises and cold water
sinks
Ocean Water Currents
Changes in Ocean Currents
– El Nino – the warming of water
in the Pacific Ocean
– La Nina – the cooling of water
in the Pacific Ocean
Causes Changes in Weather
El Nino Weather
• Rain and flooding along
the Pacific Coast
• Tornadoes and
thunderstorms in South
US
• Fewer than normal
hurricanes in the
Atlantic
La Nina Weather
• Snow and rain on the
west coast
• Cold weather in Alaska
• Warm weather in the
rest of the USA
• Drought in the south
west
• More hurricanes in the
Atlantic
Wind currents
Warm air rises and cool air sinks
Wind Currents
• Created by differences in
Air pressure
• Caused by unequal heating
of the Earth from the sun
• Equator – Warm, less dense
air
– Low air pressure
• Poles – Cold, more dense air
– High air pressure
Atmospheric/Air Pressure
• The force of the air
pushing on any surface.
• Measured in Millibars
• Decreases with altitude
• Changes with air
temperatures
• Creates wind!
Barometer – Measures Air Pressure
Air Pressure Weather Map
Isobars – Lines on a weather map that show
equal Atmospheric Pressure
• H = High Pressure
L = Low Pressure
Convection Cells of Air
Create Winds
Jet Streams
High-speed winds that can reach up to
500 km/hour high up in the sky.
Wind Speed
• Measured by an anemometer
Digital
Weather Map showing Isobars and
Windspeed/Direction
Air Masses – large bodies of air that
have similar temperature and
moisture throughout
Types of Air Masses
• Continental - form over land; dry
• Maritime - form over water; wet
and
• Tropical - form in a tropical region;
warm
• Polar – form in a polar region; cold
Air Masses
• mP – Maritime Polar
Cold and Wet
• cP – Continental Polar
Cold and dry
• mT – Maritime Tropical
Warm and Wet
• cT – Continental
Tropical
Warm and Dry
Air Masses
Fronts
• Boundary that forms between two different air
masses
– 4 types of fronts: Cold, Warm, Occluded,
Stationary
Cold Front
• When a cold air mass replaces a warm air mass
• Produces colder temperatures and more
precipitation
Warm Front
•When a warm air mass replaces a cold air mass.
•Creates warmer temperatures and some
precipitation.
Weather Map
Humidity
The amount of moisture or water vapor in the air.
Relative Humidity
• Relative Humidity – the amount of moisture
the air contains compared with the maximum
amount it can hold at a particular temperature.
Measuring Humidity
• Psychrometer
– Measures Relative Humidity
• Hygrometer
– Measures Humidity
Psychrometer
Severe Weather
• Weather that can cause property damage and
even death.
– Thunderstorms
– Tornadoes
– Hurricanes
Thunderstorms
• Intense weather systems that produce strong
winds, heavy rain, lightning and thunder
• Occur when warm, moist air rises rapidly in an
unstable atmosphere.
• Can cause high winds,
hail, flash floods,
and tornadoes.
Tornadoes
• A rotating column of air that has high wind speeds
and low central pressure that touches the ground.
• Starts as a funnel cloud
formed from a cumulonimbus
cloud
• Produced by thunderstorms
• 75% occur in the US
Wall Cloud
Wall Cloud – Take Cover
Hurricanes
• Most powerful storms on Earth
• Form in warm ocean waters by the equator
• Fueled by warm water
and moist air
• Die out over cold water
and land
Hurricanes, Typhoons, Cyclones
Form in warm ocean waters by the equator