Flashcards in Climate Deck (83):
Lowest layer of Earth’s atmosphere (Earth’s surface -> approx 15km), contains majority of atmosphere’s mass (~80%) and where majority of weather occurs
Atmospheric layer above the troposphere, containing ~20% of atmosphere’s mass, extending to about 50 km above the earth’s surface
Sun emits shortwave radiation (insolation)
Very hot object (only one: Sun) → shortwave radiation
Visible, UV, infrared, shorter wavelengths
Earth emits longwave radiation to the space
Cooler objects (everything else) → longwave radiation
A combination of visible, UV and infrared light from the sun, from 0 to over 2000 nano metres
There is a split between shortwave and longwave radiation
The rate at which energy reaches the earth’s surface from the sun which is about 1370 W m-2
Insolation (incoming solar radiation)
Measured in units of watts per square meter (W/m2)
Varies mainly because variable ‘solar angle’
Global radiation is the total short-wave radiation from the sky falling onto a horizontal surface on the ground. It includes both the direct solar radiation and the diffuse radiation resulting from reflected or scattered sunlight.
solstice solar angle
The angle at which the sun hits the Earth perpendicularly. This angle reaches a maximum angle 23.5 Degrees during the winter and summer solstices.
Earth’s distance from the Sun: perihelion (nearest – Jan 3); aphelion (farthest - Jul 4). Variation in distance ~ 3.4 %.
The equinox is a day where both day and night are equal with the sun vertical to at equator. Meaning 12 hours of daylight and 12 hours of darkness. Occurs twice a year. (sep 22-23 & mar 21-22)
The proportion of short wave radiant energy scattered upward by a surface. It is an important property of a surface because it measures how much incident solar energy will be absorbed. “Reflectivity” 0-1
The energy budget deals with how Q* (net allwave radiation is used). (i.e climate)
urban vs. rural temperatures
Rural areas have more evapotranspiration and more Qe (water evaporated by convection) because we have a lot of leaves. There is less energy to heat the air and therefore the surface is cool.
Urban temperatures are warmer than rural areas because the energy is stored rather than consumed by process such as evaporation, transpiration as there is infrastructure and water is channeled resulting in dry surfaces. Heat stored in building materials is released at night
urban heat island
Is a city that is significantly warmer than it's surrounding rural areas due to human activities (CO2 emissions and buildings which absorb more heat during the day)
Heat island tends to persist over night
Parks reduce heat
Urban areas in deserts usually do not exhibit heat islands, where irrigated vegetation may make the city cooler
a measure of the difference between continental and marine climates characterized by the increased range of temperatures that occurs over land compared with water.
land and water contrasts
Land heats and cool quickly.
Water heats and cools slowly.
The loss of energy from the earth is slowed down by greenhouse gases in the atmosphere. Thus, Earth is warmer than it would be without these greenhouse gases.
The infrared atmospheric window is the overall dynamic property of the earth's atmosphere, taken as a whole at each place and occasion of interest, that lets some infrared radiation from the cloud tops and land-sea surface pass directly to space without intermediate absorption and re-emission, and thus without heating the atmosphere
Describes the balance between incoming and outgoing radiation. At latitude lower than 40 degrees, annual net radiation is positive, while it is negative at higher latitudes.
Rapidly uplift warm fronts (as they are denser). Characterised by short periods of heavy rain; can involve lightening (due to rapid uplift), storms, or tornadoes.
Faster than warm fronts.
The mid-latitude cyclone is a synoptic (general) scale low pressure system that has cyclonic (counter-clockwise in northern hemisphere) flow that is found in the middle latitudes (not a hurricane or tropical storm).
a process by which the cold front of a rotating low-pressure system catches up the warm front, so that the warm air between them is forced upwards off the earth's surface between wedges of cold air.
The development or strengthening of a cyclonic circulation in the atmosphere (a low pressure area)
a body of air with horizontally uniform levels of temperature, humidity, and pressure. They are distinguished by the latitudinal location and type of surface of their regions.
an extensive region of the earth's surface where large masses of air having uniform temperature and humidity conditions characteristic of the region originate.
Stable air resists uplifting and mixing. Often air temperature increases with altitude (precipitation is unlikely to occur)
Unstable air, convectional mixing and uplifting of air readily occur. Air temp decreases with altitude
(uplift will cause cooling and this can result in precipitation)
The dewpoint temperature is the temperature at which the air can no longer "hold" all of the water vapor which is mixed with it, and some of the water vapor must condense into liquid water. The dew point is always lower than (or equal to) the air temperature.
A diagram showing the relative frequency of wind directions at a place.
Pressure gradient force
The pressure-gradient force is the force which results when there is a difference in pressure across a surface.Winds move from high to low pressure, across isobars.
(The deflective force - coriolis force - offsets the pressure gradient force. Because the wind is deflected it now flows parallel to isobars = geostrophic wind.)
An anemometer is a device used for measuring wind speed.
The effect is driven by the force of earth rotation creating a force deflecting moving objects like, winds, tides and ocean currents, to their right in northern hemisphere and to their left in southern hemisphere. (noted that the coriolis force offsets the pressure gradient force)
The gradient wind is a balance of the Pressure Gradient Force, centrifugal and Coriolis. A geostrophic wind becomes a gradient wind when the wind begins flowing through curved height contours. The curving motion introduces a centrifugal (outward fleeing) force.
Geostrophic winds come about because pressure gradient force and Coriolis force come into balance after the air begins to move. A geostrophic wind flows parallel to the isobars.
instrument measuring atmospheric pressure, used in forecasting the weather and determining altitude
Friction acts at the surface, the effect of friction decrease with altitude. Also, winds at the surface aren’t as strong as those at higher altitudes.
Frictional force reduces the wind speed nearer the surface.
Frictional force reduces the Coriolis effect.
Friction changes the direction of the geostrophic wind.
As a result wind flow across the isobars.
When the wind swirls anti-clockwise in the northern hemisphere or clockwise in the southern hemisphere
When the wind swirls clockwise in the northern hemisphere or anti-clockwise in the southern hemisphere
Ocean heat transport
Driven mostly by wind blowing over the surface.
However, currents move slowly.
Lag behind wind speed so often called drifts
When winds cause surface waters to diverge from a region resulting in the upwelling of colder nutrient water producing cooler temperatures along the coast.
a warm wind which blows up a steep slope or mountainside, driven by heating of the slope through insolation
The movement of seawater in a pattern of flow dependent on variations in temperature, which give rise to changes in salt content and hence in density. Thermohaline convection loop. Warm surface waters flow into the North Atlantic, cool and sink to the deep Atlantic Basin
The trade winds are the prevailing pattern of easterly surface winds found in the tropics, within the lower portion of the Earth's atmosphere, in the lower section of the troposphere near the Earth's equator. The trade winds blow predominantly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere, strengthening during the winter and when the Arctic oscillation is in its warm phase
the belt of prevailing westerly winds in medium latitudes in the southern hemisphere
a large-scale atmospheric convection cell in which air rises in medium latitudes, typically about 30 degrees north or south
Inter Tropical Convergence Zone (ITCZ)
a belt of low pressure which circles the Earth generally near the equator where the trade winds of the Northern and Southern hemispheres come together. Where warm humid air ascends. The ascending edge of Hadley Cells.
The equatorial band where there is atmospheric instability (sudden changes in weather) due to rising humid air. As a result, winds are calm. Correlates with the ITCZ.
Found at latitudes 30 Degrees North and South (between trade winds and westerlies), known for calm air, less precipitation: due to subtropical highs (gyres) found at these latitudes.
The polar easterlies are the dry, cold prevailing winds that blow from the high-pressure areas of the polar highs at the north and south poles towards low-pressure areas within the Westerlies at high latitudes.
Sea breeze cell
The sea breeze is a strong thermally- direct circulation cell that occurs in the day time.
Similar to the land/sea breeze in that it results from differential heating.
In the day, heating of the mountains is more intense and that results in air coming up from the valley (valley wind)
Subtropical high pressure belt
is a significant belt of atmospheric high pressure situated around the latitudes of 30°N in the Northern Hemisphere and 30°S in the Southern Hemisphere.
Mountain and Valley winds
Day - upslope (mountain wind)
Night - downslope (valley wind)
A narrow variable band of very strong predominantly westerly air currents encircling the globe several miles above the earth. There are typically two or three jet streams in each of the northern and southern hemispheres.
Develop in the upper-air westerlies, bringing cold, polar air equatorward and warmer air poleward.
Where airflows or ocean currents meet, characteristically marked by upwelling (of air) or downwelling (of water).
Cold flow of air travelling downward or down a slope (gravity driven). In Antarctica often 14-30 m/s.
An irregularly occurring and complex series of climatic changes affecting the equatorial Pacific region and beyond every few years, characterized by the appearance of unusually warm, nutrient-poor water off northern Peru and Ecuador, typically in late December. The effects of El Niño include reversal of wind patterns across the Pacific, drought in Australasia, and unseasonal heavy rain in South America.
La Niña is the positive phase of the El Niño Southern Oscillation and is associated with cooler than average sea surface temperatures in the central and eastern tropical Pacific Ocean.
Sea Surface Temperature Anomalies
simply transient events, not part of specific patterns or trends.
Eg; El Nino is an SST anomaly (abnormally warm temps appearing off Peru's coastline)
Southern Oscillation Index
Air pressure difference between Tahiti and Darwin (weather stations)
El Nino- Southern Oscillation (ENSO)
irregularly periodical variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting much of the tropics and subtropics. The warming phase is known as El Nino and the cooling phase as El Nina
A casual connection between meteorological or other environmental phenomena which occur a long distance apart
The Walker circulation, also known as the Walker cell, is a conceptual model of the air flow in the tropics in the lower atmosphere (troposphere).
An abrupt temperature gradient in a body of water such as a lake, marked by a layer above and below which the water is at different temperatures.
Adiabatic cooling is the process of reducing heat through a change in air pressure caused by volume expansion. In data centers and other facilities, adiabatic processes have enabled free cooling methods, which use freely available natural phenomena to regulate temperature
water which collects as droplets on a cold surface when humid air is in contact with it.
Air rising over mountain.
Change in temperature (cooling) alters the relative humidity.
Clouds forms and possibly precipitation.
Intercepting slope = windward slope (wetter). p
Leeward slope - drier (rainshadow)
Convectional Rainfall, the sun heats the ground and warm air rises. As the air rises it cools and water vapour condenses to form clouds.
Develop over warm ocean surfaces (≥28 degrees celsius) between 8 and 15 degrees latitude, migrate westward and curve toward the poles.
Characteristics; central ‘eye’(clear skies and calm winds)
Air descends from high altitudes, warming.
Wind speeds are highest at the ‘eye wall’
Winds spiral outward creating high wind speeds.
Storm gains energy from the release of latent heat.
Dies when removed from water, latitude belt and approaching land (with friction)
The term for a tropical cyclone in the western hemisphere.
In January high pressure over the land produces dry winds.Air is flowing towards the ITCZ.
The term for a tropical cyclone in western pacific and Asia
In July the position of the ITCZ moves North.
Low pressure over the land causes winds to flow off the ocean.
This brings heavy rainfall.
tropical cyclone tracks
The positions of where cyclones were and their future positions based on strength of high- and low- pressure systems.
It measures tropical cyclone intensity.
Categories 1 to 5 (5 is most devastating)
Measured by central pressure, storm surge and mean wind speed.
A glacial episode during a past geological period
An interglacial period (or alternatively interglacial) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene interglacial began at the end of the Pleistocene, about 11,700 years ago
Proxy data is data that paleoclimatologists gather from natural recorders of climate variability, e.g., tree rings, ice cores, fossil pollen, ocean sediments, coral and historical data.
Little Ice Age
The Little Ice Age is a period between about 1300 and 1870 during which Europe and North America were subjected to much colder winters than during the 20th century. The period can be divided in two phases, the first beginning around 1300 and continuing until the late 1400s.
A spot or patch that appears from time to time on the sun's surface, appearing dark by contrast with its surroundings