Midterm Flashcards
Define Meteorology
The study of the atmosphere and its phenomena
Define Weather
the current state of the atmosphere (e.g. cloudy, sunny etc..)
Define Climate
Long-term average of weather, normally 30 years (e.g. tropical, desert etc..)
Define Wind
Movement of air (speed and direction)
1 knots = 1.85 km/h = 0.51 m/s
westerly wind: wind blowing from west
Define Pressure
Force/area
Sea level pressure = 1013.25 mb (millibars) = 1013.25 hPa (hectoPascals)
Define Density
Mass of air molecules/volume
Define Temperature
Degree of hotness or coldness (ºC, ºF)
ºC + 273 = ºK (Kelvin: absolute scale)
How much of the air is in the bottom 30km
99% of air is the lowest 30 km
What are the permanent gases and their percentages?
-Nitrogen (N2): 78% (by volume)
Oxygen (O2): 21%
Argon<1%, Neon, Helium, Krypton, Hydrogen
How is Nitrogen in the atmosphere added and removed?
decaying biological (plant and animal) matter Removal: biological process (soil bacteria, plankton)
Hows Oxygen in the atmosphere added and removed?
Creation: photosynthesis
Removal: oxides (O2 combines with other substance), decaying bio matter, respiration
What are variable gases in the atmosphere and what are some examples?
The concentration changes over time and space
- CO2 - 0.04%
- Methane (CH4),
- Ozone (O3),
- CFC’s,
- Aerosols (dust, soot, etc).
- Water Vapour (H2O)
How is carbon dioxide added and removed from atmosphere?
Creation: vegetation decay, exhalation, combustion, volcanos, deforestation
Removal: photosynthesis (land and ocean), chemical weathering (rain and snow can react with silicate minerals in rocks), dissolves in oceans
Define Aerosols
Tiny particles, solid or liquid suspended in the air
Anthropogenic and natural sources of aerosols?
Natural: volcanoes, fires, windblown dust, biogenic
Human: fossil fuel combustion
Can water be in all 3 states in the atmosphere?
yes
Is water a powerful green house gas?
yes
Which layer of the atmosphere has the convection current? (The thing that controls weather?
Troposphere (Lowest 11km)
What caps the troposphere?
The Tropopause ( a transitional layer, higher in equator and lower in pole also higher in summer and lower in winter.)
Which layer of the atmosphere is a temperature inversion?
stratosphere (11 - 50 km above sea level) and thermosphere (>90km)
What creates the temperature inversion?
O3 : absorbs Ultra Violet (UV) radiation from Sun - warms stratosphere
What is the stratosphere capped by?
Stratopause
Does temperature increase or decease with height in the thermosphere? ( on of the highest level of atmosphere)
increase (Temp inversion)
If density of water is 1000 kg/m3, then calculate how many kilogram of water in a tank with a volume of 3 m3?
Density (ծ) = 1000 kg/m3 Volume (V) = 3 m3 Mass (M) = ? ծ = M / V M = V * ծ M = 1000 kg/m3 * 3 m3
Answer: M = 3,000 kg
Calculate pressure exerted by a box on a floor which has length and width of 2.0 m and 1.0 m, respectively and the box exerts 1000 N force on the floor.
Force (F) = 1000 N Area (A) = 2.0 m x 1.0 m = 2.0 m2 Pressure (P) = ? P = F / A P = 1000 N / 2.0 m2 Answer: P = 500 N/m2
Define Energy
Energy is defined as an ability or capacity to do work
Kinetic Energy = energy of motion.
E = ½*mv2
m = mass of the object, v = velocity
Kinetic energy is directly proportional to the velocity.
What is temperature proportional to?
Temperature of air is proportional to the kinetic energy of air molecules
What is potential energy?
Potential to conduct work, energy possessed by an object because of its position
PE = mgh m = mass, g = acceleration due to gravity (9.8 m/s2), h = height above ground
What is radiation energy caused by?
Due to solar radiation (short-wave) which warms the earth and emits energy (long-wave) back to space.
Is some portions of the solar radiation reflected/absorbed in the atmosphere before reaching the Earth?
Yes
Does incoming energy must balance outgoing energy?.
Yes
Define Conduction
Heat transfer through direct contact (molecule to molecule).
Define Convection
Heat transfer by mass movement of a fluid (anything that has loosely moving molecules, can move easily from one place to another, e.g. air, water).
Define Ratiation
Heat transfer by electromagnetic waves (possess magnetic and electrical properties), that release energy when the waves are absorbed by an object.
What are the 3 ways heat transfer in the atmosphere?
- Conduction
2.Convection - Radiation
(Know This!)
What is vertical movement of air called?
convection
What is horizontal movement of air called?
advection
Is short wave radiation low or high energy?
High energy
Does every objects that has a temperature
greater than 0 K emit radiation?
Yes
Do hot or cold objects emit more radiation
Hot
Define black body radiation
An object that absorbs all radiation that strikes it and emits the maximum possible radiation
Do the sun and the earth behave as black bodies?
Yes,
Sun and Earth absorb and emit nearly 100% efficiency for their respective temperature, behave as blackbodies.
What is the Stefan-Boltzman Law and what does it mean?
- Law of radiation
- States that all objects with temperature grater than absolute zero emit radiation that is proportional to the fourth power of their absolute temperature.
E = σT4
E = total amount of radiation emitted by an object per square meter (Watts/ m2)
σ = a constant called the Stefan-Boltzman constant = 5.67 x 10-8 Watts m-2 K-4
T is the temperature of the object in K
What is Wien’s Law and what does it mean?
-It states that the wavelength of maximum emitted radiation by an object is inversely proportional to the object’s absolute temperature (e.g. higher the temperature, shorter the wavelength).
λmax = W/T
λmax = wavelength (µm)
W = 2897 µm K
T = temperature (K)
What is protecting the earth from becoming frozen planet?
- The Atmosphere (greenhouse gases)
- Power GHGs are: Methane (CH4), Carbon Dioxide (CO2), Ozone (O3), Water Vapour (H2O)
Define the greenhouse effect
- The warming of an atmosphere by absorbing and emitting thermal radiations.
- The gases mainly responsible for Earth’s atmosphere greenhouse effect are water vapour, Carbon dioxide and Methane, acting as a blanket for the radiation.
Are different gases selective in the wavelengths of radiation they absorb?
Yes,
Does water vapor and CO2 absorb mostly incoming(shortwave) or outgoing (long wave) radiation
Long wave
Does O3 absorb mostly incoming(shortwave) or outgoing (long wave) radiation
Shortwave
What Happens to the Incoming (Shortwave) Radiation?
- Absorbed: ground, clouds, atmosphere (warms)
- Scattered (Diffuse): clouds, air: in all directions
- Reflected: clouds, ground, air: back to where it came from.
- Albedo: reflectivity of surface for short wave radiation (mirror 100%, snow 75-80%, thick clouds 60-90%) depends on surface characteristics (see Table 2.2 in Text) (climate change implications?)
- Transmitted (Direct): passes through to ground
Do clouds reflect shortwave or long wave radiation?
Shortwave
Are Clouds good absorbers of IR radiation ?
Yes (they can close the atmospheric window)
During daytime, why are cloudy days cooler?
Shortwave radiation cannot make it to the ground to heat earths surface due to clouds absorbing and emitting radiation.
During night (esp. during winter), why are cloudy, calm nights warmer than clear nights?
Clouds act as a greenhouse, they keep heat low to the ground which slows the drop in temperature.
What is positive feedback?
Something that reinforce effects of initial signal
What is negative feedback?
Something that suppress effects of initial signal
Are low and high altitudes in a net energy surplus or deficit?
- High = deficit = cold climate
- Low = surplus = Hot climate
What is heat capacity
The ratio of the amount of energy absorbed compared to the associated temperature change.
Example: If 10 calories of energy increases 2°C water temperature, then heat capacity of water is:
10 calories / 2 °C = 5 cal per °C
What is specific heat
The heat capacity of substance per unit mass.
Example: if 1 cal energy is required to raise 1 gram of water temperature by 1 °C then specific heat of water is 1 cal/gram.
What is latent heat?
The amount of heat required to change the state of a substance at constant temperature.
->When a substance changes from one state to another latent heat is absorbed or released during the changing process.
Describe the hydrologic cycle?
- Evaporation 2. Condensation 3.Precipitation 4.Run off
If: Evaporation > Condensation
Then: solution will be ___________saturated
sub saturated
Cooling promotes _____
Condensation
Heating promotes ________
Evaporation
Define saturation with regards to moisture in air
the level of water vapour in the air is at the maximum possible at a given T and Pressure.
What does an RH of 50% mean? how would you calculate it?
- air contains ½ of water vapour required to saturate it
- RH = (actual water vapour pressure) / (saturation vapour pressure) * 100%
IF: T increases, saturation vapour pressure increases, then RH will _________
Decrease
Define Dew Point
A temperature to which unsaturated air would have to be cooled down (with no change in pressure or water vapour content) for saturation to occur
High Dew Point, _______ amount of water vapour
High
Can dry air (low Dew Point) can have high RH?
yes, (example: cold polar air)
Define Dew
Temp of air cools to Temp Dew Pt (saturation),
if Temp surface < T Dew Pt : condensation on surfaces,
tiny water droplets: “dew”
Occurs on clear, calm nights when surface is cold relative to air
Define frozen dew
Dew forms then freezes (Tair cools to < 0 C)
When does frost occur
Temp of Dew Pt ≤ 0 C, and
Temp of air cools to Temp Dew Pt and further cooling occurs, water vapour directly to ice (deposition): Frost Point
Define Condensation Nuclei
tiny particles (natural: sea salt, or human caused: air pollution, smoke) :
->More nuclei, more condensation
What is haze?
When condensation occurs at an RH less then 100 due to hygroscopic (water attracting) nuclei.
Can there be no condensation at a RH of 100
Yes if hydrophobic nuclei are present `
What is fog
Clouds on the surface of the earth
How does fog form
- Cooling: Tair cooled below its saturation point (TDew Pt)
- Evaporation and Mixing: adding water vapour by evaporating into air and mixing to distribute (raise TDew Pt to Tair )
How does continuous fog formation occur?
As water vapour is removed through condensation during fog formation (T Dew Pt lowers), air must continue to be saturated either by continual cooling or by evaporation and mixing.
What is radiation fog?
IR emitted at night from surface->surface cools, air near surface cools to TDew Pt and becomes saturated
- Occurs at night when: clear sky: surface temp colder than air, light winds (< 5 knots - mix moist air to cold surface: more fog)
- Thickest at sunrise (why?), dissipates (“burns off”) from surface upwards as sunlight warms ground (evap of droplets near ground, more warming, more evap)
- In valleys, Radiation Fog called Valley Fog: cold, dense air drains to low areas (valleys)
What is advection fog
- Warm, moist air moves over cool surface (example: cool ocean, air cooled to (TDew Pt ) and becomes saturated
- Occurs night or day
What is up slope fog
- Moist air pushed up slope: expands and cools to TDew Pt and becomes saturated
- Occurs night or day
- Common at seaside (moist air moving on shore and rising over land)
- Upper side of valley sidewalls following rainstorms, moist air lifted and cooled by upslope winds.
What is Evaporation and Mixing Fog? What is steam fog?
- water vapor added by evaporation, then mixes with dry air
- T Dew Pt increases when T Dew Pt = T air : saturation
Steam Fog – a type of evapo and mixing fog.
-cool air over warm water (lake, heated pool)
warm moist air rises, mixes and evaporates into cooler, drier air above raising T Dew Pt to Tair : saturation
condensing vapour appears as rising “Steam”
common in late fall: warm water relative to land
Dew and frost: form on _____ nights when temperature of objects drop below TDew
Clear
What is a cloud and when does it form?
- Visible aggregate of water droplets or ice crystals suspended in air
- Formed when moist air is lifted and cooled
What are the four major cloud groups
High, medium, low and ones with vertical development.
What are the shapes of Cirrus - Stratus - Cumulus - Nimbus -
Cirrus - curl
Stratus - layer
Cumulus - heap
Nimbus - violent rain
Clouds that start with the suffix cir are where in the atmosphere?
High
Clouds that start with the suffix alto are where in the atmosphere?
middle
Clouds that start with the word stratus in their name are where in the atmosphere?
low
Clouds that start with the suffix cum are where in the atmosphere?
vertically developed
How would you identify a cirrus cloud
- Thin, fibrous, layered cloud.
- Mainly composed of ice crystals
What does stability and instability mean in regards to out atmosphere?
Stable: vertical motion suppressed
Unstable: vertical motion enhanced
