chapter 7 Flashcards
what pourcentage of earths water is in the atmosphere
0.03%
Hydrologic cycle, or water cycle
the movement of water throughout the atmosphere, hydrosphere, lithosphere, and biosphere
Hydrogen bonding
the positive (hydrogen) side of a water molecule attracts the negative (oxygen) side of another, polarity
Surface tension
allows a steel needle to float lengthwise on the surface of the water, even though steel is much denser than water, this surface tension allows you to slightly overfill a glass with water
Capillarity
caused by hydrogen bonding; when a towel draws water through its fibres because hydrogen bonds make each molecule pull on its neighbour
what happens after 4°C with water
water behaves differently from other compounds, it expands as more hydrogen bonds form among the slowing molecules, creating the hexagonal crystalline structure characteristic of ice
Phase change
the change in phase, or state, among ice, water, and water vapour; involves the absorption or release of latent heat
Melting and Freezing
phase changes between solide and liquid
Condensation
water vapour in the air becomes liquid water
Evaporation
liquid water becomes water vapour
Vaporization
when water is at boiling temperature and become water vapour
Deposition
water vapour attaches directly to an ice crystal, landing to the formation of frost
Sublimation
ice changes directly to water vapour
ice phase
It contracts in volume but increases in density, (as the same number of molecules now occupy a smaller space), 80 calories is needed to change phases
why does ice floats
Pure ice has 0.91 times the density of water, so its floats, without that, much of earth’s freshwater would be bound in masses of ice on the ocean floor, it contains air bubbles
Latent heat
heat energy is stored in one of three states - ice, water, or water vapour. The energy is absorbed or released in each phase change from one state to another. Heat energy is absorbed as the latent heat of melting, vaporization, or evaporation. Heat energy is released as the latent heat of condensation and freezing (or fusion)
liquid phase
100 calories is needed for a change of phase
Latent heat of vaporization
the heat energy absorbed from the environment in a phase change from liquid to water vapour at the boiling point
Latent heat of condensation
the heat energy released to the environment in a phase change from water vapour to liquid
Latent heat of sublimation
the heat energy absorbed or released in the phase change from ice to water vapour and vise versa, absorbe 680 cal for a change of phase
gas phase
540 calories is needed to change the gas phase into liquid phase, under normal sea level pressure
what happens when global temperature rise
evaporation increases from lakes, oceans, soils, and plants, amplifying the concentration of water vapour in the atmosphere and strengthening the greenhouse effect over Earth
Effect of climate change on water
as water vapour increases, precipitation patterns will change and the amount of rainfall will likely increase during the heaviest precipitation events, A 7% vapour will increase for every 1°C of warming
Humidity
the amount of water vapour in the air, it is primarily a function of the air temperature
Relative Humidity
the ratio of water actually in the air (content) to the maximum water vapour possible in air (capacity) at that temperature; expressed as a percentage
Saturation equilibrium
equilibrium in the maximum amount of water vapour that can exist in a volume of air at a given temperature, and the rates of evaporation and condensation are the same
Saturation
state of air that is holding all the water vapour that it can hold at a given temperature, known as the dew-point temperature
Dew-point temperature
the temperature at which a given mass of air becomes sautéed, holding all the water it can hold. Any further cooling or addition of water vapour results in active condensation
Frost point
the temperature at which the air becomes saturated, leading to the formation of ice on surfaces
why does the rate of evaporation varies from morning to afternoon
because relative humidity changes with temperature
dawn
highest humidity, first light before sunrise
Vapour pressure
that portion of total air pressure that results from water vapour molecules, expresses in millibars (mb)
Saturation vapour pressure
air that contains as much water vapour as possible at a given temperature
why warm tropical air over the ocean can contain so much water vapour
For every temperature increase of 10°C, the saturation vapour pressure in air nearly doubles, thus providing much latent heat to power tropical storms, or not a lot of precipitation in the poles
Specific humidity
The mass of water vapour (in grams) per unit mass of air (in kilograms) at any specified temperature
Mixing ratio
the ratio of the mass of water vapour (grams) per mass of dry air (kilograms)
Maximum specific humidity
the maximum mass of water vapour possible in a kilogram of air at any specified temperature
increase as the air temperature increases
Hair hygrometer
an instrument for measuring relative humidity, based on the principale that human hair will charge as much as 4% in length between 0% and 100% relative humidity
Sling psychrometer
a weather instrument that measure relative humidity using two thermometers - a dry bulb and a wet bulb - mounted side by side
Stability
refers to the tendency of an air parcel either to remain in place or to change vertical position by ascending (rising) or descending (falling)
The two opposing forces that decide the vertical position of a parcel of air
buoyant force (upward), and gravitational force (downward)
The stability or instability of an air parcel depends on two temperatures
the temperature inside the parcel and the temperature of the air surrounding the parcel
how does An ascending parcel of aire react
tends to cool by expansion, responding to the reduced pressure at higher altitudes, Descending air tends to heat by compression
Diabatic
means occurring with an exchange of heat
Adiabatic
means occurring without a loss or gain of heat
Normal lapse rate
is the average decrease in temperature with increasing altitude (6.4°C/1000m)
Environmental lapse rate is the actual lapse rate at a particular time and place
Dry adiabatic rate (DAR)
the rate at which «dry» air cools by expansion as it rises or heats by compression as it falls, less then saturated
Moist adiabatic rate (MAR)
the rate at which an ascending air parcel that is moist, or saturated, cools by expansion
what does atmospheric stability affects
cloud formation and precipitation patterns
Unstable
12°C x 1000 m-1, the aire parcel continues to rise through the atmosphere because it is warmer (less dense and more buoyant) than the surrounding environment and cool, the less-dense air parcel will continue to lift
Conditionally unstable
7°C x 1000 m-1, the air parcel resists upward movement, unless forced, if it is less than saturated. But if the air parcel becomes saturated and cools at the MAR, it acts unstable and continues to rise, the environmental lapse rate is greater than the moist adiabatic lapse rate and less than the dry adiabatic lapse rate
Stable
5°C x 1000 m-1, the air parcel has a lower temperature (is more dense and less buoyant) than the surrounding environment. The denser air parcel resists lifting, unless forced by updrafts or a barrier
clouds and fog are fundamental indicators of what
of overall conditions, including stability, moisture content, and weather
Cloud
aggregation of tiny moisture droplets and ice crystals that are suspended in air and are great enough in volume and concentration to be visible
fog
simply a cloud in contact with the ground
Moisture droplet
a tiny water particle that constitutes the initial composition of clouds. Each droplet measures approximately 0.002 cm in diameter and is invisible to the unaided eye
what can happen as an air parcel rises
it may cool to the dew-point temperature and 100% relative humidity
Cloud-condensation nuclei (CCN)
microscopic particules necessary as matter on which water vapour condenses to form moisture droplets; can be sea salts, dust, soot, or ash (natural CCN, meteoric dust, windblown clay and slit, volcanic material, etc…, anthropogenic CCN, combusting products like sulfur and nitrogen)
Creation of clouds need
presence of saturated air, cloud-condensation nuclei, cooling (lighting) mechanisms, condensation occurs
Two principal processes for raindrops and snowflakes
- the collision coalescence process; involving warmer clouds and falling coalescing droplets
- Bergeron ice-crystal process; in which supercooled water droplets evaporate and are absorbed by ice crystals that grow in mass and fall
Stratus or cumulus
low clouds, ranging from surface levels up to 2000 m in the middle latitudes, (when yield precipitation, they are nimbostratus)
Stratocumulus
near the end of the day, lumpy, greyish, Loe-level clouds
Altocumulus
middle-level clouds, represent a board category that includes many different types
Cirrus
clouds at high altitude, principally composed of ice crystals
Cumulonimbus
also called thunderheads because of their shape and their associated lightning, thunder, surface wind gusts, updrafts and downdrafts, heavy rain, and hail
stratiform
flat and layered clouds with horizontal development
cumuliform
Puffy and globular clouds with vertical development, dense, heavy
cirroform
Wispy clouds, usually quite high in altitude and made of ice crystals hairlike, feathery
Radiation fog
formed by radiative cooling of a land surface, especially on clear nights in areas of moist ground; occurs when the aire layer directly above the surface is chilled to the dew-point temperature, thereby producing saturated conditions
Rime fog
a fog that consists of supercooled water droplets that turn into rime first on contact with freezing objects
Ice-crystal fog
a type of fog that develops at very low temperatures in a continental arctic air mass. visibility is seriously limited when the aire becomes full of ice crystals that have formed by sublimation
Advection fog
active condensation formed when warm, moist air moves laterally over cooler water or land surfaces, causing the lower layers of the air to be chilled to the dew-point temperature
Upslope fog
forms when moist air is forced to higher elevations along a hill or mountain and is thus cooled
Valley fog
the settling of cooler, more dense air in low-lying areas; produces saturated conditions ans fog
Evaporation fog
a fog formed when cold air flows over the warm surface of a lake, ocean, or other body of water; forms as the water molecules evaporate from the eater surface into the cold, overlying air; also known as steam fog or sea smoke
