Weather and Climate

Climate vs. Weather

• Weather: Short term state of the atmosphere.– Temperature, humidity, cloud cover, precipitation,

winds, visibility, air pressure, air pollution, etc… • Climate: The average weather conditions in an

area over a long period of time– Described by temperature and precipitation

Measurement Definition Instrument

How hot or cold the air is

The weight of the air

How fast the wind is blowing

Where the wind is blowing from

Amount of water vapor in the air

Amount of rain or snow that falls

Temperature Thermometer

Air Pressure Barometer

Wind Speed Anemometer

Wind Direction Weather Vane

Humidity Hygrometer

Precipitation Rain Gauge

MEASURING

WEATHER

Measuring WeatherInstruments used in measuring weather in the upper atmosphere

• Radiosonde:– a package of instruments that is carried aloft by balloons to measure upper atmospheric conditions, including

temperature, dew point, and wind velocity– sends measurements as radio waves to a receiver that records the information.– When the balloon reaches a very high altitude, the balloon expands and bursts, and the radiosonde parachutes

back to Earth.

• Radar: radio detection and ranging– a system that uses reflected radio waves to determine the velocity and location of objects– The newest Doppler radar can indicate the precise location, movement, and extent of a storm. It can also

indicate the intensity of precipitation and wind patterns within a storm.

• Weather Satellites:– Satellite images provide weather information for regions where observations cannot be made from ground.– The direction and speed of the wind at the level of the clouds can also be measured by examining a continuous

sequence of cloud images.– Satellite instruments can also measure marine conditions.

• Computers– Solving very difficult mathematical equations– Store weather data– Can provide information that is useful in forecasting weather changes

Measuring Weather Continue

Measuring ClimateMethods of Studying Past Climates

Method What is measured What is indicated Length of time measured

Ice Core Concentrations of gases in ice and melt water

High levels of CO2 indicate warmer climate; ice ages follow decreases in CO2

Hundreds of thousand of years

Sea-floor Sediment

Concentration of 18O in shells of microorganisms

High 18O levels indicate cool water; lower 18O levels indicate warm water.

Hundreds of thousand of years

Fossils Pollen types, leaf shapes, and animal body adaptations

Flower pollens and broad leaves indicate warm climates; evergreen pollens and small, waxy leaves indicate cool climates. Animal fossils show adaptations to climate changes.

Millions of years

Tree Rings Ring width Thin rings indicate cool weather and less precipitation

Hundreds to thousands of years

Measuring Climate Continue

• Long term weather measurements– Satellites

• Geological Evidence– Evidence of glaciation– Rock layers

Climate Graph

Creation of Wind that eventually leads to weather and climate.

Flashlight Mini Lab

• Flashlight Demo:– Predictions: Which will have the most energy per given area, the

90 degree or the 30 degree angle flashlight? – Hold the flashlight at 90 degree angle and about 10 inches above

your paper• Draw an outline around the beam• Count the number of squares:

– Hold the flashlight at 30 degree angle and about 10 inches above your paper• Draw an outline around the beam• Count the number of squares:

• Which has the most energy per given area? – 90 degree

Direct vs. Indirect Sunlight

• Sun gives off the same amount of radiation and stays the same temperature!

• The tilt of the Earth (23 ½ degrees) determines the concentration of the sun in a given area– Small area = large concentration– Big area = less concentration

http://www.sci.uidaho.edu/scripter/geog100/lect/02-energy-seasons-atmosphere/02-pt-1-solar-energy.htm

HOW DIRECT AND INDIRECT RELATES TO CLIMATES

Winter in Northern Hemisphere

• Tilted away from the Sun• Cooler Temperatures = Cooler

Climates• Higher latitudes• Sun’s rays hit Earth at a smaller

angle• Solar energy is spread out over a

larger areawindows2universe.org

Summer in Northern Hemisphere

• Tilted towards the Sun• Higher Temperatures = Warmer

Climates• Lower latitudes• Sun’s rays hit Earth around 90

degrees• Solar energy is more direct,

smaller areas windows2universe.org

HOW DIRECT AND INDIRECT RELATE TO WIND

Uneven Heating of the Earth

• Is warm air more or less dense the cold air?– Less Dense

• If you have cold air at the poles and warm air at the equator where do you think each air mass will want to move and why?– Cold air mass will move toward the warm air mass and the warm

air mass will move toward the cold air mass because of convection.• Convection: the movement of matter due to differences in the density

that are caused by temperature variations; can result in the transfer of energy as heat.

– Convection currents/Density currents • The convection of air is a key piece in creating wind.

Atmospheric Pressure(Air Pressure)

• atmospheric pressure: the force per unit area that is exerted on a surface by the weight of the atmosphere– decreases as altitude increases– changes as a result of differences in temperature

and in the amount of water vapor in the air

Atmospheric Pressure Continue

Atmospheric Pressure Continue

Pressure Gradient

• Uneven heating of the Earth’s surface creates pressure gradients.

• Cause air to move form high pressure areas to low pressure areas creating wind

• http://www4.uwsp.edu/geo/faculty/ritter/animation/atmosphere/pressure_gradient.gif

THE WIND’S PATH

Question

• Why doesn’t the wind blow straight to the North and South pole from the equator? – Rotation of the Earth, which we call the Coriolis

Effect

Coriolis Effect• Coriolis effect: the curving of the path of a moving object from

an otherwise straight path due to Earth’s rotation• Circulation of atmosphere and ocean currents are effected. • http

://www.youtube.com/watch?v=aeY9tY9vKgs&feature=related • Hold the spherical device in your hand and rotate it

counterclockwise (West to East) and look at it from the top. Which way is it rotating?– counterclockwise

• Now keep rotating it counterclockwise (West to East) and look from the bottom, which why is it rotating?– Clockwise

Coriolis Effect Continue

High and Low Pressure Wind Directions

• High pressure winds move outwards

• Low pressure winds move inwards

• Both are curved because of the Coriolis Effect

Cyclones and Anticyclones

• The hole column of air around a high or low pressure.

• Cyclones: when air moves into low areas it collides or converges. The collision causes the air to lifted and then diverge. – Part of how storms are created

• Anticyclones: air converges towards the surface and then once it reaches the surface it is forced out (divergence)– Nice weather

Global Wind Patterns • trade wind:

• Blow from east to west • Latitudes 30º latitude to the

equator in both hemispheres• Westerlies:

• Blow from west to east • between 30º and 60º latitude in

both hemispheres• descending air moving toward the

poles is deflected by the Coriolis effect

• Polar easterlies:• Blow from east to west • between 60 and 90 latitude in both

hemispheres• Surface winds created by the polar

high pressure are deflected by the Coriolis effect

• Each of the three types of winds are affected by the High and Low pressures

• Both winds and pressure zones have an impacted on determining climates around the global.

Moist air rising

Moist air rising

Moist air rising

Dry air Sinking

Dry air Sinking

Dry air Sinking

Dry air Sinking

Jet Stream

• a narrow band of strong winds that blow in the upper troposphere

• These wind exist in the Northern and Southern Hemisphere.– Subtropical jet stream. – Polar jet streams:

• reach speeds of 500 km/h• can affect airline routes and the paths of

storms.

HOW OCEAN ARE EFFECTED BY WIND

How Global Winds Effect Ocean Surface Currents

• Trade winds cause the ocean currents to be pushed westward across the tropical latitudes of all three major oceans.

• Westerlies cause the ocean currents to be pushed eastward in the higher latitudes.

Coriolis Effect on Oceans

• Cause gyre– Huge circle of moving ocean water found above

and below the equator– Northern hemisphere they move clockwise– Southern hemisphere they move counterclockwise

El Nino

• Trade wind either weaken or switch direction• Cause upwelling to weaken or stop off the

coast of South America and the fish die from heat and lack of nutrient from the upwelling process.

• Causes flooding in South America (Peru) and droughts in Indonesia and Australia.

• Mess up the weather for the rest of the Global.