Causes of Weather - Suffolk Public Schools Blogblogs.spsk12.net/7925/files/2014/08/Unit_9_day-3-causes.pdf · 2017-02-14 · evolution of the atmosphere and the interrelationship

Causes of Weather

Focus Question

How’s the weather today?

VA SOL

SOL 2 (Infused) The student will demonstrate scientific reasoning and logic by– a.analyzing how science explains and predicts the interactions and

dynamics of complex Earth systems; and

SOL 12 The student will investigate and understand the origin and evolution of the atmosphere and the interrelationship of geologic processes, biologic processes, and human activities on its composition and dynamics. Key concepts include:– d. atmospheric regulation mechanisms including the effects of density

differences and energy transfer

The student will investigate and understand that energy transfer between the sun and the Earth and its atmosphere drives weather and climate on Earth. Key concepts include– d. weather phenomena and the factors that affect climate including

radiation and convection

Enduring Understanding

Energy transfer between the Earth’s surface

and the atmosphere creates the weather.

The atmosphere remains in balance until

acted on by an outside force.

Causes of Weather

As mentioned before the various atmospheric

processes we call weather are caused by

the ongoing balancing and vital

redistribution of Earth’s heat energy

throughout the planet

Weather

– Weather is the current state and short

term variations in the state of the

atmosphere

Takes place over minutes, hours, days,

weeks, months

Causes of Weather

Climate is the long term variations for a

particular area

– Averaged over 30 years or more of weather

data

Striking Angle

Since the Earth is tilted and spherical in

shape the Sun’s energy strikes our surface

unevenly. The lower angle receives less

energy

Striking Angle

The area between the tropics receives more

direct sunlight

The area near the poles receives sunlight at

a lower angle and the energy is spread

over a larger area

Striking Angle

Coriolis Effect

Redistribution of Wealth

Without the atmosphere this energy

imbalance would continue and the tropics

would be very hot and the poles very cold

year round

– The oceans store the majority of heat at

Earth’s surface

Redistribution of Wealth

Temperature differences in the air result in

differences in density which the cause

upward and downward movement

The convection currents of the

atmosphere redistribute the heat energy as

air over the warmer regions rises, cools,

then descends over cooler regions.

Redistribution of Wealth

This movement causes

weather

Redistribution of Wealth

Energy moves from source to sink:

high to low

Redistribution of Wealth

Air Masses

An air mass is a large body of air that takes

on the characteristics of the body over which

it forms. They can form over either land or

water and are classified according to their

source regions

Air Masses

Continental Tropical (cT) air masses contain warm, dry air that forms over warm areas of land

Maritime Tropical (mT) air masses contain warm, humid air that forms over warm areas of the ocean

Continental Polar (cP) air masses contain cold, dry air that forms over cold areas of land

Maritime Polar (mP) air masses contain cold, humid air that forms over cold areas of the ocean

Arctic (A) air masses are basically the same as cP, but much colder and are associated with extreme cold

North American Source Regions

All five main air mass types can be found in

North America because of our close

proximity to the source regions associated

with each type of air mass

North American Source Regions

Continental Tropical (cT) air forms over the

desert of the southwest United States and

Mexico

North American Source Regions

Maritime Tropical (mT) air forms over the

southern Atlantic, Gulf of Mexico, and

southern Pacific oceans

North American Source Regions

Continental Polar (cP) air forms over the

interior of Canada and Alaska

North American Source Regions

Maritime Polar (mP) air forms in the

northern Pacific and Atlantic oceans

North American Source Regions

Arctic (A) air develops over the extreme

northern regions of the continent

Stability and Air Mass Movement

Air masses do not stay in one place

indefinitely. They move and transfer their

heat from one area to another establishing a

balance of heat throughout the planet

Stability and Air Mass Movement

Air mass modification occurs when the

moving air mass changes to become more

like the surface over which it travels

Heat and moisture are exchanged with the

surface as the air mass travels over it

Stability and Air Mass Movement

Eventually the air mass will become

modified to the point it is indistinguishable

from the new surface over which it is

traveling and simply becomes part of the air

over the new source region