Earth’s Weather and Climate. Our Weather and Climate Weather –The condition of the atmosphere at...
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Transcript of Earth’s Weather and Climate. Our Weather and Climate Weather –The condition of the atmosphere at...
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.
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
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.
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
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
• 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!
Air Pressure Weather MapIsobars – Lines on a weather map that show
equal Atmospheric Pressure
• H = High Pressure L = Low Pressure
Wind Speed
• Measured by an anemometer
Digital
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
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.
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
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