What Causes Our Weather?

From the Sun to Our Earth!

Global movement of matter is driven by the properties of water and energy

Heat Transfer:– Radiation– Conduction– Convection

Convection is the primary mechanism of energy transfer in the atmosphere, oceans and asthenosphere

What Causes Climate and Seasons

The shape of the planet and the tilt Milankovitch Cycles: Like a top the Earth wobbles

and the length of the elliptical orbit changes every 100,000 years as well as the tilt, causing different latitudes to receive more or less sunlight

What are the Major Global Convection Cells?

Hadley Cells: Start at equator and rise to about 30-45 N/S latitude (trade winds)

Rainforests form where air rises

Deserts form where air descends

Convection Cells

Ferrel Cells: Exist from 30-60 degrees latitude N/S (Westerlies)

Polar Cells: Cold, very dry dense air (Polar Easterlies)

Jet Streams: Extremely fast moving winds found at boundaries of convection cells

What is the Coriolis Effect?

How do our oceans affect weather?

Trade winds created by the Coriolis Effect apply friction to the surface of the ocean and drag water in the same direction.

Thermohaline currents: Temperature and salinity affect density of the ocean consequently causing currents (cold salty water is denser)

Twice a day the gravitational pull from the moon causes high tides

What is El Nino-Southern Oscillation (ENSO) ?

Rise in temperature of 0.5 Celsius degrees more than normal in the Eastern Pacific Ocean near the equator, usually beginning around December (hence the name, “Christ Child”)

Occurs at irregular intervals of 2-7 years and has usually lasted one or two years, but has been coming more frequently.

Disrupts global weather patterns Triggered by Southern Oscillation

What are the Effects of El Nino

The deeper, warmer water in the east limits the amount of nutrient-rich deep water normally surfaced by the upwelling process

Since fish can no longer access this rich food source, many of them die off

What happens in the atmosphere?

Tropical thunderstorms are fueled by hot, humid air over the oceans

The hotter the air, the stronger and bigger the thunderstorms

The east coast of southern Africa and Australia often experiences drought during El Nino

Describe economic consequences!