Weather and Climate

Sections

27.1 - Heating and cooling of Earth

27.2 - Global Winds and Ocean Currents

27.3 - Weather Patterns

27.4 - Storms

27.5 - Weather and Climate

Big Idea for the Section

We have just finished studying how humans have affected the Earth’s climate... now we move onto understand the different seasons and how they are related to the

Earth's direction from the

Sun.

Directions Latitude- lines run parallel to the equator and are labeled in degree North or South.

-Lines measure distance from the equator in degrees.

Longitude- Lines run vertically from the north pole to the south pole

Prime Meridian- Longitudinal line that runs through Greenwich, England

- 0 degrees longitude

- East: 1-179 of the Prime

Meridian

-West: 1-179 of the Prime Meridian

Meridian

0 Degrees and 180 Degrees are not labeled East or West

Earth’s Temperature

At high numbered latitudes (north or south), Solar radiation is less intense and therefore, less heating takes place.

Question: What season is it here?

Temperature and Rotation

1) As Earth rotates, the portion of the globe facing the sun warms as it absorbs more solar radiation than it emits.

2) Earth constantly emits some of the absorbed energy as Infrared Radiation

3) The emmission of heat cools the dark side of the planet.

Rotation

- Axis: The imaginary line that passes through its center which it rotates around.

- Rotation: Earth’s spinning on its axis- Brings about night and day.

Earth’s Seasons

Earth’s axis is at an angle to the sun, allowing seasons to occur.

12 noon on the first days of the seasons

27.2 Global Winds and Ocean Currents

Convection Currents: Circular movement of different temperature fluids

-Fluids move because of differences in their density.

Convection Currents Cont.

Thermals: small convection currents in the atmosphere

- Thermals form on a local level but can also form giants convection currents in the atmosphere.

- These form as a result of the temperature difference between the equator and the poles

Coriolis EffectBending of air or water currents.

-Occurs because of the Earth’s rotation

Global Winds

Trade Winds, Prevailing Westerlies, Polar Easterlies:

Question: Why do theses winds blow E or W, when Cells move air N or S?

What Causes the Wind?

The pressure differences are caused by uneven heating of the earth’s surface by?

HeatDifferent parts of earth get different amounts of energy each day.

Causing: Uneven heating which results in pressure differences which results in?

Oceanic Currents:

Global wind patterns and Earth’s rotation (Coriolis Effect) cause surface ocean currents to move in large circular patterns called Gyres.

These currents move huge amounts of energy (heat) and therefore change climates.

Oceanic Layers and Waterfalls

-Caused by differences in temperature and salinity

2 questions: Which is more dense? a) fresh or salt water?

b) Cold or warm water?

c) Cold Fresh or hot salt?

d) Cold Fresh or cold salt?

Differences in temp. and salinity are just differences in?

Why is the Ocean so cold here?

- Coastal upwelling brings cold, nutrient rich water from the ocean bottom to the surface along our coast. ¸

- Caused by the prevailing winds

Our upwelling makes our coast have a very productive Marine life

27.3 Weather Patterns

Weather Patterns

-Three important factors that shape the weather in a given region are: temperature, pressure and water

- A sling psychrometer can measure water in the air.

Phase changes of water

-Water in the atmosphere exists in all three states of matter

-Ice

-Liquid

-Gas

Cloud Formation- Clouds form when warm moist air is cooled

Three Cloud Types:

1) Cumulus Clouds- form when convection causes rising pockets of air in the atmosphere

2) Stratus Clouds- form when a large mass of stable air gradually rises, expands and cools.

Cirrus Clouds- thin lines of ice crystals high in the sky, above 6,000 meters.

-They are just a thin streak of white across a blue sky.

Air Masses and Fronts

Air Mass: large body of air with consistent temperature and moisture characteristics throughout

Front: Where two different air masses meet

Low and High Pressure Areas

a) Low Pressure: tends to be associated with cloudy rainy weather.

b) High Pressure: Tends to be associated with clear sunny weather

Temperature Inversions: “Spare the Air” Days- bad air pollution days

-Caused by temperature inversions which trap warm air under cold air

Ground Fog: Warm moist air over cold ground

Coastal Fog: Warm moist air over cold water

Chapter 27.4

STORMS

StormsThunderstorms: Air near the ground is strongly warmed and rises high into the troposphere.

-As the air rises, it cools and condenses, forming a large cumulonimbus cloud.

Storm cells: cloud droplets become large enough to fall as rain.

El Nino (ENSO): A change in the Pacific Ocean current caused by weakening Trade winds

Problems El Nino causes a number of problems...

Also affects our weather

-Warm and dry in NW (drought)

- Cooler and wet in SW

- Landslides in Southern California

La Nina:

Opposite of El Nino

- Stengthening trade winds- Colder waters- Wetter and cooler NW- Warmer and Dryer SW