wind all lecture notes

Solar Wind

Primarily consists of charged particles such as protons and electrons, moves outward from the sun to space, and has little effect on Earth due to its magnetic shield. Moves at speeds as high as 900 km/h and at a temperature of 1 million degrees celsius.

Planetary Wind

Any wind system that exists on Earth, either due to solar radiation or various forces, and is associated with most of the meteorological variables that affect our weather and climate.

Greenhouse Gas

An atmospheric constituent that traps outgoing terrestrial radiation, including water vapor, carbon dioxide, methane, nitrogen oxide, ozone, and CFCs.

Geological Control

Emissions from volcanic eruptions dominated the atmosphere, with carbon dioxide and methane being the primary gases. The atmosphere is dynamic and has changed over time.

Geological to Biological Control

life appeared 3.8 billion years ago under anaerobic conditons. It was the age of bacteria. Then abrupt change occurred 2.3 billion years ago. With the age of bacteri, carbon dioxide and water were converted into oxygen and organic compounds. As a result oxygen began to accumulate in the atmosphere. Then aerobic life forms appeared and flourished (biological control).

Gaia Hypothesis

Proposed by James Lovelock, the hypothesis suggests that life modifies the environment to best suit itself. It states that atmospheric constituents have been controlled by life to optimize conditions for life on Earth. GH postulates that the atmospheric constituents have been controlled by life to optimize conditions for life. Whatever conditions you put the Earth under, it will try to survive

Gaia hypothesis used to explain the switch from anaerobic to aerobic conditions

Change was bound to happen. Early Archean sun produced 30% less energy. Then solar output gradually increased. Early Earth with high levels of oxygen and methane had a strong greenhouse gas effect which led to conditions warm enough for life. After 2.3 billion years solar output has increased and Earth is becoming too warm. The switch to aerobic life reduced the greenhouse gases and cooled the planet. We now have lower levels of carbon dioxide than early Earth.

Anthropogenic Control

Man made changes. Life arrives on Earth and the sun’s energy converted plant material using photosynthesis. Decaying plants are not fully oxidized and are converted to coal under geological pressure. With the emergence of human civilizations and industrialization, human activities have had a profound impact on the atmosphere.

Boreas

the wind of the North

Eurus

the wind of the East

Notus

the wind of the South

Zephyrus

the wind of the West

Natural Greenhouse Gas

a part of the atmosphere that traps outgoing radiation, includes water vapour, methane, carbon dioxide, nitrogen oxide, ozone, and CFCs. is needed for the survival of life on Earth

Enhanced Greenhouse Gas

extra greenhouse gases are trapped in the Earth’s atmosphere which causes a warming effect and is harmful

Temperature

measured by thermometer

Pressure

measured by barometer

Humidity

measured by hygrometer or psychomotor

Wind speed

measured by anemometer

Wind direction

measured by weather vane

precipitation

measured by rain gauge, snow gauge, radar

Anthropogenic

anything related to humans (man made changes)

Midlatitude Cyclones

Commonly referred to as "low pressure centers" or "frontal systems," these major weather makers occur in the midlatitudes (35° - 60°) and are larger than hurricanes but have less intense winds. They can occur approximately every 4-7 days and can have thunderstorms and tornadoes associated with them. The ingredients to midlatitude cyclones are fronts.

Cyclones

Associated with clouds, precipitation, and winds, cyclones are characterized by low pressure centers and exhibit a characteristic movement from west to east. The first sign of a cyclone approaching from the west is the appearance of cirrus clouds roughly 12 to 24 hours in advance of the warm front.

Climatology of the Midlatitudes

The polar front region, located between the Polar and Ferrel cells, is the battleground between cold front and polar jet stream.

Air Masses

Midlatitudes are the battle ground between continental polar (cP) and maritime tropical (mT) air masses. cP air is stable, while mT air is unstable.

Fronts

Occur at the division/collision center between air masses.

Polar Front Theory

The polar front is a semi-continuous boundary separating cold polar air from more moderate mid-latitude air. Midlatitude cyclones (wave cyclones) form and move along the polar front in a wavelike manner, with low pressure or cyclones being the principle weather makers at midlatitudes.

Great Lake Storms

Major weather events that impact lake levels, cause erosion and sediment transport, and result in ship and property damage. Approximately 20% of midlatitude cyclones have their origins at the Great Lakes.

Hurricanes vs Midlatitude Cyclone

Hurricanes: energy source is latent heat release, have warm cores, weaken with height, have a central eye with sinking air, winds are strongest at surface, isobars are more circular, have no fronts, the centre pressure drops, and occur near the ocean.

Mid lat cyclonesL energy source is contrast of air masses, have cold cores, intensify with height, air rises in the centre, winds are stronger aloft, isobars are less circular, have fronts, centre pressure drops, and occur aloft.

Perfect Storm

A storm that occurred in October 1991, also known as the Halloween Storm, which was formed by the combination of cold air from the US West meeting a warmer air mass from the Atlantic. It involved the remnants of Hurricane Grace and later transformed into an unnamed hurricane.

Storm of the Century

A storm that occurred in 1993, starting as a frontal wave off the Texas Coast and intensifying into a deep open wave cyclone over Florida. It caused significant damages, including a deep snow blanket, damage to homes, and the loss of lives. It occurred because within a couple hours many low pressure centres formed, and cold and warm fronts were developed as well as pivot points.

1998 Ice Storm

A midlatitude cyclone that resulted in freezing rain and caused significant damage in Quebec. It was the worst natural disaster in Canada, causing loss of lives, power outages, and economic losses.

1999 Blizzard of Toronto

A series of four storms that passed to the south of Toronto and resulted in larger than normal snowfall. It was an unusual event that does not appear to be part of a trend. The winds swept across Lake Ontario gathering moisture and energy which led to large r than normal snowfall.

Freezing Rain

A type of storm that can develop into freezing rain, starting as a midlatitude cyclone. It occurs when mT air mass overrides cP air, leading to precipitation that forms aloft and freezes upon contact with the cold ground.

anti-cyclonic

characterized by clear skies and light winds and are caused by sinking air that can cause very high temperatures in the summer

Stationary Front

Stationary fronts are stable due to a lack of latent heat. Low pressures, horizontal wind shear, and are identified by alternating blue triangles and red semi circles

Cold Front

cold fronts occur when cold air pushes into a warm air mass. Designated by blue line with triangles facing warm air. Heavy precipitation when the cold air pushes the warm mT air up. There is a strong temperature gradient, shift in wind direction, and change in pressure

Warm front

Warm fronts occur when warm air pushes into a cold air mass. Gentle precipitation. Designated by red line with semi circles pointing toward cold air

Occluded fronts occur when the cold front catches up with the warm front.

Occluded fronts occur when the cold front catches up with the warm front. Most intense part of the storm. Warm air is forced above the surface. Associated with alternating blue triangles and red semi circles on one side, and the colour purple.

Step One Polar Front Theory

stationary front with a strong horizontal wind shear. cP on the tip of the stationary front coming and meeting mT air. As soon as they come close to the stationary front it causes a disturbance

wind shear

horizontal gradient of wind direction and can be unstable

step two polar front theory

low pressure centre develops. Cold anticyclonic fronts, and warm cyclonic fronts develop from opposite sides. Cold air pushes, and warm air rises. There is a collision between cP and mT. Precipitation starts

pivot point

lowest local pressure and low pressure centre

step three polar front theory

warm front and cold front are more intense. Pivot point develops and so does a circular isobar. A wave fully develops and moves East or Northwest. The centre pressure continues to drop and large bands of precipitation form. A warm sector forms in the region between fronts, which becomes a fuel centre for storms as the warm air brings latent heat.

step four polar front theory

pivot point is even narrower, isobars are more closely spaced, centre pressure continues to drop. Precipitation band continues to grow longer, the faster moving cold front catches up with the warm front which reduces the size of the warm sector.

step five polar front theory

the storm intensifies. an occluded front develops because the cold from catches up with the warm front. the pressure continues to drop. It is the most intense part of the storm with widespread precipitation and comma shaped clouds.

step six polar front theory

storm begins to dissipate after occlusion. The source of the energy mT air has been cut off because there is no more latent heating.

Thickness of the Atmosphere

The atmosphere is only 2% of Earth's thickness, with most of it confined to the lowest 100 km above sea level. Because of the shallowness of the atmosphere, its motions over large areas are horizontal. .

Horizontal Wind speeds

a thousand times greater than vertical wind speeds

Layers of the Atmosphere

The atmosphere is divided into four distinct layers: troposphere, stratosphere, mesosphere, and thermosphere. Each layer has unique characteristics and temperature changes with height.

Clouds

Concentrations of liquid water droplets or ice crystals that form by the condensation of water vapor in saturated air. Clouds can remain suspended in the air and cover half of the Earth's surface at any given time.

Low Clouds

surface to 2000 metres

Wind

The movement of air in an "ordered" fashion, primarily due to an uneven distribution of air pressure. Air moves from areas of high pressure to low pressure, creating a pressure gradient force (PGF) that drives wind.

Coriolis Force

A fictitious force due to the rotation of the Earth, causing a deflection of wind to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The Coriolis force influences the direction of wind.

Geostrophic Wind

Upper-level winds that occur approximately 1 km above the Earth's surface. Geostrophic winds are in balance between the pressure gradient force and the Coriolis force, resulting in parallel wind flow.

Surface Winds

Winds that occur below 1 km above the Earth's surface and are influenced by friction from obstructions like buildings and trees. Friction disrupts the balance between the pressure gradient force and gravity, which creates an angle and causes the surface wind to bend

Troposphere

Lowest layer. Temperature declines as height increases in this layer, because as we move up we are moving away from Earth’s core which is the source of heat. It is an oil mixed layer where 90% of the Earth’s weather phenomena occurs.

Stratosphere

second layer of the atmosphere. Temperature now increases as height increases because the ozone concentration is the highest in this layer

Ozone

inorganic molecule (O3) that absorbs solar radiation

tropopause

transition state between troposphere and stratosphere

mesosphere

third layer and is also an oil based layer. Temperature decreases with height because heat that was absorbed at the base is dispersed by vertical air motions

thermosphere

fourth layer and is very close to the sun. Temperature increases as height increases because solar radiation in this layer is absorbed by nitrogen oxide and oxygen molecules which releases kinetic energy of motion. (molecules move faster)

Cloud concentration nuclei (CCN)

must be present for water to condense out of saturated air.

Middle clouds

2000 m to 7000m

High clouds

7000+ m

Stratus, strato-

layer clouds

Cumulus, cumulo

puffy or heap clouds

cirrus, cirro

high, curly clouds

nimbus, nimbo

rain clouds

alto

middle clouds

isobars

lines of constant pressure in the atmosphere

weak winds

widely spaced isobars with high pressure centres

strong winds

closely spaced isobars with low pressure centres

vertical pressure

associated with changes in vertical flow

vertical pressure gradient

dominant in lower half of the atmosphere, is about 1 mb per 10m

horizontal pressure

associated with changes in horizontal flow

horizontal pressure gradient

dominant in the upper atmosphere (mid troposphere) is about 1mb per 6000 metres

gravity v pressure gradient force

explains why are not blown away by wind, or why wind doesn’t fall on the surface level. gravity acts downwards while the PGF acts upwards, creating a balance

low pressure surface

wind moves counter clockwise which causes convergence at the bottom and divergence at the top. strong winds with closely spaced isobars

high pressure surface

wind moves clockwise which causes divergence at the bottom and convergence ay the top. weak winds with widely spaced isobars

air mass

large body of air whose properties of temperature and moisture are fairly uniform in any horizontal direction at any given altitude. tend to cover many thousands of kilometres

source region:

the area where an air mass originates

pressure gradient force

formed when wind travels from an area of high pressure force to an area of low pressure force.

Rising Air

Air that moves upward, leading to cooling and condensation. Produces clouds, air pressure and temperature decreases with height

Sinking Air

Air that moves downward, leading to warming. Pressure increases as the height decreases.

Air Pressure

The force exerted by the weight of the atmosphere on a given area.

Synoptic Scale

Weather events or features that cover hundreds or thousands of square kilometers, such as cyclones and hurricanes.

Mesoscale Phenomena

Weather events or features that span between 10 and 1000 kilometers, such as tornadoes and thunderstorms.

Local Scale

Weather events or features that are less than 100 kilometers in size, such as land and sea breezes.

Anti-Cyclones

High-pressure systems characterized by winds that have high center points, widely spaced isobars, and travel clockwise.

Cyclones/Depressions

Low-pressure systems characterized by closely spaced isobars and winds that blow counterclockwise.

Global Wind Circulation

The movement of air on a global scale, driven by the uneven heating of the Earth's surface.

One Cell Theory

Named after George Hadley, it is the idea that there is only one large overturning atmospheric cell in each hemisphere, with air rising at the equator and sinking at the poles.

Three Cell Theory

The idea that there are three distinct atmospheric cells in each hemisphere, including the Hadley Cell, Ferrel Cell, and Polar Cell. the idea that energy doesn’t travel from the equator to the pole

Intertropical Convergence Zone (ITCZ)

An area of rising air near the equator, characterized by heavy precipitation.

Trade Winds

Winds that blow from northeast to southwest in the tropics, forming part of the surface component of the Hadley Cell.

Subtropical High

High-pressure systems that occur at 30°N and 30°S, characterized by sinking air and little to no precipitation.

Westerlies

Winds that blow from west to east in the midlatitudes, forming part of the surface component of the Ferrel Cell.

Polar Front

The boundary between polar air and midlatitude air, where low-pressure systems often form.