Meteorology: the study of Earth’s atmosphere

Meteor – In ancient Greek – meant “High in the air”

Current meanings still apply• Meteor – astronomical entity that falls from the sky• Clouds, raindrops, snowflakes, fog, dust, etc. are all

(technically) meteors• Precipitation is known as HYDROMETEORS• Electricity is known as ELECTROMETEORS• Smoke, haze, dust known as LITHOMETEORS

Weather vs. Climate•Weather is the current state of the atmosphere• Climate is the long term variation in weather for a particular area.

Movement of Air

1. Wind is caused by the uneven heating of the Earth and its atmosphere

2. These temperature differences lead to the creation of high pressure and low pressure areas

3. Wind – the movement of air from an area of high pressure to an area of low pressure

Wind Formation:

1. Tilt in the rotation as Earth orbits around the sun

2. Curved surface of the Earth

3. The albedo of the surface

1 and 2 result in differences in angle of

insolation ( incoming solar radiation )

Equator receives the most radiation, poles receive the least

Cause of Temperature Differences:

1. Warm air is less dense than cold air so it rises

2. Cold air sinks and moves along the Earth’s surface

Density of Air:

The tendency of a moving object to follow a curved path rather than a straight one due to Earth’s rotation

Only perceived, the object/air is moving along a straight line, but the Earth is moving underneath it

Coriolis Effect: – deflection of winds and objects as a result of the earth rotating on it’s axis from west to east.

Weather Systems

Weather systems are created by global wind patterns

•Global Wind Patterns are created by the fact that the earth rotates on it’s axis, and as a result of the majority of earth being covered by water.

Global Wind Patterns – caused by Coriolis, and Convection

1. Doldrums - Windless zone of the equator due to hot air rising straight up

2. Trade Winds 00– 300 North and South Latitude•30 ° N/S Air SINKS, moves towards equator to the west, get warmer - “Horse latitudes” •Gets to the equator – runs into the Trade Winds in the Southern Hemisphere, and they RISE (ITCZ – InterTropical Convergence Zone) – Equator

3. Prevailing Westerlies 300 – 600 responsible for most of the weather changes we get here in the U.S.•Called Westerlies – but they move in toward the east (Winds named for the direction from which they originate)

4. Polar Easterlies 600 – 900 Poles. Areas of high pressure over the poles moving from east to west.

- Where they meet warmer air of westerlies they produce stormy region of FRONTS

Global Wind Patterns – caused by Coriolis, and Convection

Jet Streams – Narrow belt of strong winds near top of troposphere, blow from west to east, average 60-110 miles per hour, position changes daily and seasonally, major effect on weather

Jet streams push the air masses along quickly.

When the air masses run into each other, fronts occur.

All weather occurs at a frontal boundary

Most significant Jet Stream is called the Subtropical Jet Stream – which is created when the trade winds meet the prevailing westerlies.

A monsoon is a seasonal change in the direction of the prevailing, or strongest, winds of a region.

Monsoons cause wet and dry seasons throughout much of the tropics.

Monsoons are most often associated with the Indian Ocean.

Monsoons always blow from cold to warm regions. The summer monsoon and the winter monsoon determine the climate for most of India and Southeast Asia.

Monsoon

Concept: Land heats up and cools down faster than water

Local Winds:

Wind blowing from land to sea during the night

Caused by:

• Water cools off slower so it warms the air above it causing it to rise

• Air above land moves in to replace it

Land Breeze:

Wind blowing from sea to land during the day

Caused by:

• Land warmed faster by the sun

• Air warmed above land rises

• Air above water moves in to replace it

Sea Breeze:

Valley Breeze - During day warm valley air moves up the slopes of the mountains

Mountain breeze - At night colder mountain air moves down into the valley

Mountain and Valley Breezes