Humidity & Weather Processes PDF

Humidity- the amount of water vapor in the air - Relative humidity (RH)- the relationship between the volume of the air parcel and the volume of the water vapor - Lower, less relative humidity- less water vapor in proportion to the air parcel - Higher relative humidity-...

Humidity- the amount of water vapor in the air - Relative humidity (RH)- the relationship between the volume of the air parcel and the volume of the water vapor - Lower, less relative humidity- less water vapor in proportion to the air parcel - Higher relative humidity- more water vapor in proportion to the air parcel - As air parcels heat, the volume of air parcels expand. Generally, this is why you can get higher humidity in hotter places - Ex: Florida, swampy Virginia - DOES NOT MEASURE THE AMOUNT OF WATER VAPOR, MEASURES THE PROPORTION OF DIFFERENT VOLUMES - Compares the amount of water vapor present to the maximum amount that the air can hold at that temperature - Expressed as a percentage Can change RH in two ways: - Gain/lose moisture - Change in temperature Specific aka absolute humidity- is the amount of water vapor held by a parcel of air (UoM is g/kg) - Measures the literal weight of the water vapor - If air cools, capacity is reduced - This is why we see precipitation as air cools! - If air warms, capacity is increased - Higher at low latitudes, lower at high latitudes Dew point- the temperature at which air, with a given humidity, will reach saturation (when cooled without changing its pressure) Adiabatic Processes: - The Dry Adiabatic Lapse Rate: - Temperature change due to a change in elevation - Has a different temperature change compared to the moist adiabatic lapse rate: - Because water has a higher specific heat capacity - 10C per 1000m OR 5.5F per 1000ft - The Moist Adiabatic Lapse Rate: - 4-9C per 1000m OR 2.2-4.9F per 1000ft Types of precipitation: - Rain, Snow, Hail, Ice storm - Atmospheric lifting: - Air has mass. If air moves, a vacuum will be created, moving everything else near it - Orographic Lifting (\"oro\" means mountain in Latin)- precipitation induced when moist air is forced vertically over a mountain - Convective precipitation- precipitation induced when moist, warm air is heated at the ground surface and rises, cools, and condenses to form water droplets, raindrops, and then rainfall - Convergent lifting- air is moving along, and two air mases collide, and then lift up - If different densities, warm and cool air front hitting each other- then lifting and then rain will occur - A lot of this in California   - Earth\'s weather happens in the troposphere, where it\'s colder as altitude rises - When air is forced upwards, it cools - The rate at which air cools, is dependent on the amount of water vapor in the air - Dry air changes by 9.8C/1000m - Moist air changes by 6C/1000m - Foehn Wind- where moist air collides with a mountain (at the given moist air adiabatic lapse rate seen above), rains, and then as the now dry air passes away from the mountain on the leeward side, will be warmer - Can cause extremely rapid warming - Even unstable slopes and avalanches - Rain, hail, snow - Rain- - Drizzle is even smaller water droplets - Can reduce visibility - Raindrops or ice crystals coalesce in rain clouds, until they fall to earth - Snow- - Ice crystals and supercooled water droplets form in clouds- ice crystals grow rapidly in this environment - Aggregate together - Large snowflakes fall - Sometimes if the air below is too warm, snowflakes arrive in the ground as raindrops melting before it reaches the ground - Hail- - As warmer air rises, Clouds grow, and water droplets undergo \"glaciation\" where ice crystals freeze, and then hailstones - Hailstones can fall through the cloud, or cycling through the hail cloud until it falls - Ex: If all sea ice melted due to global warming... - 95% of earth\'s ice is land-based - Sea levels will rise 70m - Half of the earth\'s populations live in coastal cities- all of these would be destroyed - If ice melted, lower albedo \>\> even more melting - Oceanic currents would be changes as well - Disrupted how plants and fish feed - Gulf stream would shift- Europe would become much colder, harder to grow crops - Convection cell- circular pattern, driven by rising heat and sinking cool air - Convection is a transfer of energy, through fluid - Specific type of heat transfer- it\'s not the same as radiation - Convection- ex: water is heated on a stove top, vaporizes, and transfers the energy with it, energy rises up into the atmosphere, floats upwards - If my hand is above the pot of water, the steam will hit my hand, and transfer energy as my hand heats up - Seen all over, especially in physical geography - Drawing of a convection cell - Parcel of air that heats up, and rises - As air rises, it then begins to cool down and condense. Stops rising - Don\'t fall right back down immediately because air mass is below it - Goes back down (sideways) eventually due to gravity - Air collides with the surface of the earth as it goes back down, and replaces the vacuum at the surface of the earth - Drawing: - A black line drawing of a rectangle Description automatically generated - Atmospheric pressure- pressure exerted by the atmosphere because of the force of gravity acting on the overlying column of air - Air density dependent on P and T - Atmospheric pressure decreases as altitude increases - \"high pressure systems\" on the weather report- air sinking back to the earth - \"low pressure systems\"- air rising - Wind- horizontal movement of air, aka \"advection\" - Renewable resource - Measured with anemometer - Wind direction- identified by the direction from which the wind comes - West wind blows west to east (where you are) - Measured with wind vane - Land breeze- started inland, making its way to the ocean - Ocean breeze- started on the ocean, making its way inland - Wind speed and direction determined by: - Pressure gradient - Wind- results from the horizontal motion of air from areas of high surface pressure to areas of low surface pressure - Move downhill along the pressure gradient - Usually due to uneven heating of the earth- heated air is less dense - Warm air is low pressure - Drawing of the \"isolines\": - Change of atmospheric pressure is measured along a line, at right angles to the \"isobars\" - Drawing is kind of topographic, shows different altitudes and steepness basically a. If lines are closer together, then steeper incline - Isolines- show equal lines of a variable, in the example maps- can be either pressure or altitude - Low pressure always followed by a high pressure cell. Mass in the low pressure needs to be replaced by more air - Coriolis effect- effect of the Earth\'s rotation, that acts like a force to deflect a moving object on the Earth\'s surface, where- a) it moves to the right in the Northern hemisphere, and b) it moves to the left in the southern hemisphere - Covered last week too - Friction   - Air mass- a name given to a large chunk of air, that develops certain characteristics due to where it is on the planet - Ex: Topical continental air mass- sits over the Sahara, hot and dry - Can move north towards Britain - Ex: Polar continental airmass- comes from around the North Pole, and travels over land. Can travel to Britain either from Eastern Europe, or from Scandinavia - Super cold winters, snow storms - If the airm ass travels across an ocean, it\'ll usually dramatically change - Maritime air mass that travels across the Atlantic to Britain - Mix of sunshine, hail, sleet, rain, snow - Common air mass over Britain - Warms as it travels over the sea, rises, then cools- creating clouds - A continental air mass usually will only change a little as it travels   - Game of catch example on a merry-go-round - What happens if you throw a ball while the merry-go-round moves clockwise? - Ball curves mid-air - Coriolis effect- object in motion pulled sideways, off its course - Ex: flat marry-go-round like what you\'d see on a playground - A thrown ball will no longer travel in a straight line it the merry-go-round is moving, instead its path of travel is deflected, and ends up curved (due to the rotational force) - On Earth, all objects are subjected to the Coriolis effect - Northern hemisphere- objects diverted right - Southern hemisphere- objects diverted left - Every 24 hours, wind produces x35 the amount of energy that humanity needs per day - Renewable resource - Wind energy- wind pushes blades, and translates kinetic energy into rotational energy - Then, turns a generator to create electricity - Factors determining how much energy they can produce: - Size and orientation of the blades i. Can have their rotor either on a vertical or horizontal axis 1. Vertical-picks up energy from any direction, but far less efficient 2. Horizontal- undergoes \"yawning\" as it turns to face the wind, done by the system\'s process controls - Blade\'s aerodynamic design i. Blades must be shaped to maximize efficiency ii. Modern blades are curved like airplane winds- incorporate a lift and twist - Amount of wind turning the rotor i. Amount of wind increases with altitude- so most wind turbines are pretty tall today - Offshore wind farms- contain huge amounts of turbines - 220m Diameter- largest turbine ever built in the Netherlands - Efficiency? - Since some wind must be converted into mechanical force, a turbine can only ever capture 59.3% of the wind\'s energy - Other issues: - NIMBYs don\'t like them, unsightly - Non-continuous availability of electricity- makes it harder to incorporate into current electric grids - Wind energy- most efficient, and inexpensive source of energy - As we experience advances in grid technology and energy storage, wind energy will becoming increasingly popular - Luke Howard- early 19th century - Classified \"clouds\" for the first time- originally people just called them \"essences\" - Presented a paper on clouds at 20 - Clouds and fog - Clouds- don\'t see usually in a high pressure system i. Forms in a low-pressure system - Clouds consist of water droplets, ice crystals, or both - Condensation nucleus- a tiny but of solid matter (aerosol) in the atmosphere, on which water vapor condenses to form a tiny water droplet ii. Needed in order for clouds to form - How do clouds form? - Clouds- made of water droplets and ice crystals - Form when warm, moist air encounter cool air - Clouds form differently based on different types of air lifting - Convective cloud- water has evaporated, rises, encounters cool air and condenses iii. If that cloud hits a cold front, it will rain - Clouds will move because of different air temps outside the cloud - Clouds are classified in Latin - Classifying by shape: iv. Cumulous- heap/pile v. Status- layer (short, spread out) vi. Cirrus- wispy vii. Nimbus- rain - Classified by altitude viii. High, above 20,000ft- Cirro ix. Mid, between 6500-20,000 ft- Alto x. Low, below 6500- Stratus - Put together the ALTITUDE + SHAPE xi. Ex: altocumulus is a mid-level, fluffy cloud xii. Ex: cumulonimbus cloud is a fluffy, rainy cloud - How clouds form: - Convection- intense heating of land causes the air nearer to the ground, to expand and get lighter, which causes it to rise - Lifting- when moving air encounters hills or mountains, it\'s forced upwards. Rising air cools so moist air that rises up a mountain side cools (orographic and frontal) xiii. Cool and warm air masses interact xiv. Leads to flat stratus clouds - Frontal activity- when a mass of warm air collides with a mass of cold air (a front), the lighter warm air is forced to rise above dense cold air - Convergence- air masses run into each other - Fog- a cloud that is a result of a microclimate. The result of a convection cell. - Radiation fog- formed when temperature of the air at ground level falls below dew point - Advection fog- forms when warm moist air moved over a cold surface xv. Common over oceans \"sea dog\" xvi. West Coast of US, and Canada xvii. Southern California xviii. Santa Barbara xix. San Francisco xx. Means \"sideways movement\" - **[ADVECTIONAL FOG EXAMPLE]** - 10:20 timestamp- drawing of fog formation, with San Ynez Valley, Santa Barbara, and the Pacific Ocean - Around springtime, San Ynez will see temperatures rise faster because it\'s inland xxi. In May, temperatures start rising xxii. Warm mass of air sitting above during the day xxiii. At night, the temperature drops quicker - But in SB, because of how close it is to the ocean, it takes much longer for the temperature to get super hot or super cold. More temperate because of high specific heat capacity - At night when the temperature drops, the warm air mass from above the San Ynez Valley rises, then travels over the mountains, and sits over the cool ocean current xxiv. Warm air now sitting above cool air- temperature inversion xxv. Cool air then condenses, forming a low-level cloud- FOG!!! - When the sun comes up again, San Ynez Valley heats up quicker, and the fog that was over the ocean, then travels to above SB, where it eventually burns off above the mountains -  - **[RADIATION FOG EXAMPLE (aka Tule Fog)]** - Sacramento, Bakersfield, Fresno - During the day, temperature in a valley heats up quickly (bc inland), creates a super warm air mass that then rises - Then at night, temperature in the valley cools quickly (bc) inland. Warm air mass is now sitting above cooler air - Cool air then condenses into fog - Youtube video player MORE VIDEOS 4) 27:06/ Shar my whiteboard just figured out how to use this thin s we learn hmm look YouTube - **[Difference-]** - Advection fog sits over an ocean, and then gets pulled sideways. San Francisco, Santa Barbara - Radiation fog forms in a valley. Sacramento, Bakersfield, Fresno - Local winds: - During the fall in Santa Barbara/San Francisco... this is basically the summer (Aug-Oct) xxvi. Chinook Winds: 1. Fog pattern reverses, where temperature goes down faster in the valley, but the coast is still really warm. Warm air that\'s just been sitting in the valley... 2. Will travel over the mountains, into SB, releasing latent heat... causes wildfires xxvii. Santa Ana winds- fire starters - Human impacts on clouds and precipitation - Due to pollution- increase seen in acid rain xxviii. Corrosive effect - Review of different types of lifting - Death Valley- has some of the lowest humidity in the world - **[Example drawing- Sierra Nevada]** - Death Valley- lowest point in NA, actually lower than sea-level - Air from the ocean travels over the San Ynez, then over Bakersfield, then over the Sierra Nevada mountains, orographic lifting dries out all the humidity - As air travels into death valley, losing altitude (therefore adiabatically heating), continues to heat more and more xxix. Will be extremely warm and dry at the bottom of Death Valley - Luke Howard- London Science Club - Obsessed with clouds and weather - Main insight- Clouds have many individual shapes, but have few basic forms - Naming system had to account for this instability - Compound naming - Had an immediate national impact, poets even wrote about it, and artists released series of cloud paintings at the time - Meteorology was a late developed science - Classifying clouds: - SHAPE: Cirrus, Cumulus, Stratus   - Earth\'s average surface temperature has continued rising due to climate change... - All of this is important within the context of climate change, especially trying to predict how much Earth\'s temperature will rise by - Issue- we don\'t understand aerosols and particulate matter quite well enough - Earth\'s climate sensitivity- temperature change in response to a radiative forcing - Radiative forcing- temporary difference between the energy received from the sun, and the energy radiated back out to space - Imbalance caused by GHGs - Data based on testing over hundreds of years - How cloudy was it in 1750? This problem is hard to solve - Computer modeling can kind of answer the question - Atmospheric aerosol- everywhere in the atmosphere, scatters sunlight - Clouds cannot form without an aerosol particle seed - How aerosols form in the atmosphere and their effect on clouds is poorly understood - Lack of understanding of aerosols- main reason for the lack of understanding on Earth\'s climate sensitivity, and incredible wide range of future temperature projections - CLOUD project at Cern - Steel vessel, where we can measure and observe aerosol particle formation - Help form aerosols: Sulfuric acid, ammonia, amines, biogenic vapors from trees - Potential unaccounted climate forcing agent- galactic rays - How cloudy was the pre-industrial climate? How much of the change is due to human activities? - Could some of the pre-industrial climate be influenced by the presence of galactic rays on clouds? - Clouds are visible accumulations of tiny water droplets or ice crystals in Earth's atmosphere. Clouds differ greatly in size, shape, and color. They can appear thin and wispy, or bulky and lumpy. -   - Clouds usually appear white because the tiny water droplets inside them are tightly packed, reflectingmost of the sunlight that hits them. White is how our eyes perceive all wavelengths of sunlight mixed together. When it's about to rain, clouds darken because the water vapor is clumping together into raindrops, leaving larger spaces between drops of water. Less light is reflected. The rain cloud appears black or gray. -   - Clouds form when air becomes saturated, or filled, with water vapor. Warm air can hold more water vapor than cold air, so lowering the temperature of an air mass is like squeezing a sponge. Clouds are the visible result of that squeeze of cooler, moist air. Moist air becomes cloudy with only slight cooling. With further cooling, the water or ice particles that make up the cloud can grow into bigger particles that fall to Earth as precipitation. - **Types of Clouds** - Because certain types of clouds are associated with certain types of weather, it is possible to forecastthe weather by observing and understanding these different types of clouds. -   - Clouds are classified into three main groups: cirrus, stratus, and cumulus. -   - Cirrus clouds are wispy, curly, or stringy. They are found high in the atmosphere---typically higher than 6,000 meters (20,000 feet)---and are usually made of ice crystals. Cirrus clouds usually signal clear, fair weather. Their shape often indicates the direction the wind is blowing high in the atmosphere. -   - Stratus clouds are horizontal and stratified, or layered. Stratus clouds can blanket the entire sky in a single pattern. They usually occur close to Earth. Stratus clouds often form at the boundary of a warm front, where warm, moist air is forced up over cold air. This movement produces clouds as the moist air is cooled across the entire front. The presence of stratus clouds usually means a chilly, overcast day. If precipitation falls from stratus clouds, it is usually in the form of drizzle or light snow. -   - Cumulus clouds are large and lumpy. Their name comes from the Latin word meaning \"heap\" or \"pile.\" They can stretch vertically into the atmosphere up to 12,000 meters (39,000 feet) high. Cumulus clouds are created by strong updrafts of warm, moist air. Most forms of heavy precipitation fall from cumulus clouds. The weather they bring depends on their height and size. The higher the base of a cloud is, the drier the atmosphere and the fairer the weather will be. Clouds located close to the ground mean heavy snow or rain. - **Variations** - Clouds are also classified according to how high they are in the atmosphere and what kind of weather they produce. -   - The prefix \"cirro-\" refers to clouds that lie more than 6,000 meters (20,000 feet) above the Earth. Cirrocumulus and cirrostratus clouds are two examples of these "high-level" clouds. -   - The prefix \"alto-\" indicates clouds whose bases are between 2,000 and 6,000 meters (6,500-20,000 feet) above Earth, such as altocumulus and altostratus clouds. They are considered \"mid-level\" clouds and are mostly made of liquid water droplets, but can have some ice crystals in cold enough temperatures. -   - The prefix \"nimbo-\" or the suffix \"-nimbus\" are low-level clouds that have their bases below 2,000 meters (6,500 feet) above Earth. Clouds that produce rain and snow fall into this category. (\"Nimbus\" comes from the Latin word for \"rain.\") Two examples are the nimbostratus or cumulonimbus clouds. -   - Nimbostratus clouds bring continuous precipitation that can last for many hours. These low-level clouds are full of moisture. -   - Cumulonimbus clouds are also called thunderheads. Thunderheads produce rain, thunder, and lightning. Many cumulonimbus clouds occur along cold fronts, where cool air is forced under warm air. They usually shrink as evening approaches, and moisture in the air evaporates. Cumulonimbus clouds gradually become stratocumulus clouds, which rarely produce rain. -   - **Clouds and Weather** - Certain types of clouds produce precipitation. Clouds also produce the bolt of electricity called lightning and the sound of thunder that accompanies it. Lightning is formed in a cloud when positively charged particles and negatively charged particles are separated, forming an electrical field. When the electrical field is strong enough, it discharges a superheated bolt of lightning to Earth. Most of what we consider to be single lightning strikes are in fact three or four separate strokes of lightning. -   - The sound of thunder is actually the sonicshock wave that comes when the air, heated by the lightning bolt, expands very rapidly. Thunder sometimes sounds like it comes in waves because of the time it takes the sound to travel. Because the speed of light is faster than the speed of sound, lightning will always appear before its thunder is heard. - Meteorologists measure cloud cover, or the amount of the visible sky covered by clouds, in units called oktas. An okta estimates how many eighths of the sky (octo-) is covered in clouds. A clear sky is zero oktas, while a totally overcast or gray sky is eight oktas. -   - Scientists have experimented with a process called cloud seeding for many years. Cloud seeding aims to influence weather patterns. Seeds, or microscopic particles, are placed in clouds. These seeds are artificial cloud condensation nuclei (CCN), which are tiny particles of dust, salt, or pollutionthat collect in all clouds. Every raindrop and snowflake contains a CCN. Water or ice droplets accumulate around CCN. Scientists hope that cloud seeding will allow people to control precipitation. -   - **Extraterrestrial Clouds** - Clouds exist in outer space. Clouds on Jupiter, for instance, are divided into three bands in the planet's atmosphere. The highest band, at 50 kilometers (31 miles) above the surface of the planet, is mostly clear. -   - Jupiter's middle layer of clouds is constantly moving. These storm clouds appear as bands and swirls of yellow, brown, and red. Most of these clouds are made of droplets of ammonia and ammonia crystals, mixed with phosphorus and sulfur. (These ammonia storms would be toxic on Earth.) -   - Beneath Jupiter's thick layer of ammonia clouds lies what some astrophysicists believe is a thin layer of water clouds. Scientists think there may be water clouds because bursts of lightning have been spotted in Jupiter's atmosphere. -   - Interstellar clouds, which exist in the space between planets and stars, are not really clouds at all. Interstellar clouds are areas where gases and plasma are dense and, sometimes, visible. Astronomers determine what elements are present in interstellar clouds by analyzing the light, or radiation, that comes from them. Most interstellar clouds are made of hydrogen, helium, and oxygen. The dusty "milk" of the Milky Way is an interstellar cloud between the stars of our galaxy. - Cirrus- high up - Stratus- blanket, flat - Cumulus- puff-balls, rounded - Nimbus- storm clouds - Clouds- deliver fresh water from the oceans to land. Allow for agriculture and life - 3 types of clouds: - Cumulus- big white and puffy, \"heap\", \"file - Form low to the ground - Stratus-\"layer\", flat horizontal cloud sheets - Form wide-spreading layers, reflecting sunlight - Cirrus- \"wisp of hair\", form really high up - Usually consist of ice crystals instead of water droplets - Words used to describe clouds: - Alto- high, above 2000m - Cirro- \"very high\", above 7000m - Nimbus- \"rain clouds\" - Different cloud types occupy different heights in the atmosphere - Lenticular cloud- circular, disc-like, usually form when something\'s disturbing air flow, like a mountain - \*\*discussed in-depth the extremely specific types of clouds that are more rare, maybe just memorize the major cloud naming conventions honestly - Rest of the video is niche cloud genres lol - Supercell- basically a mini tornado - **[Air pressure around the globe]** - Air pressure- air either lifting away or pushing down on us - General global patterns of air pressure - **[Building a model of global wind circulation (1st order winds)]** - Building a model of air pressure across the globe - Warm surface conditions or strongly rising air often produce low surface pressure - Cold surface conditions or strongly descending air often produce high surface pressure - **[What are the macro pressure systems across the world? ]** - How do wind and air pressure work together to create major climate zones? - The topics have surplus of solar energy- receiving most of the energy from the sun - What will this lead to? - Low-pressure system in the topics\-\-- sun heats the air, leads to convectional lifting, and therefore low-pressure systems - As this air cools down, it\'ll condense\-- with a lot of water vapor in it, since it\'s coming from the tropics - Humid, warm air- as it rises, squeezes water vapor out. - Will see low-pressure and TONS of rain as a result - Plants love this! Lots of biodiversity and biomass - After these air masses have cooled and are condense- where will they go? - Can\'t go straight down necessarily, but gravity will pull it back down - This is actually the beginning of a convection cell! -  - Because it\'s adiabatically cooled (due to a change in elevation as it went up), it will then adiabatically heat as it goes down, but will have lost water vapor - Will see dry air, and high pressure system \~30N of the equator - Will see the Sonoran Desert here- a line of our \"true deserts\", as the high pressure system filed with dry air descends back down - All true deserts happen here- Atacama, Sahara, Sonoran, etc. - At the poles, extremely cold, dense air\-\-- will see sinking air at the poles, in the form a high pressure system - **[Convection cell-]** - Will tell us about the transfer of energy from the equator to the mid-latitudes - Will be SUPER WINDY- air is constantly rushing to the tropics to replace air moved around and shifted by the convection cell - At about 60 degrees N and S- we have low-pressure cells - Will usually only get rain in a low-pressure cell - Will have a lot of storms coming out of this area - **[Hadley Cell]**- pressure cell happening from around the equator, to the mid-latitudes - Circular pattern, convection cell - Interacts with \"trade winds\" in the tropics - Story of the man and the lion fighting- who conquered who, and who got to name it? - **[ITCZ- Intertropical Convergence Zone:]** - Convergence between the tropics creates a large region of generally low pressure called the ITCZ. - This area is often wet and cloudy - Doldrums- a little line where nothing actually moves, kind of like the eye of a hurricane - **[Really severe winter storms..]** - Polar fronts are other areas of relatively low pressure, atmospheric instability, and the source of most mid-latitude storms - Warm midlatitude air colliding/converging with cold polar air at roughly 60 degrees N and S of the equator - **[All of this put together- will basically tell us where wind is going]** - Cargo ship got caught in a storm... 28,000 rubber ducks in the North Pacific - Have now washed up all over the world - Researchers have been able to study ocean currents indirectly through the rubber ducks - Ocean currents - Topography affects the motion of the currents - Surface currents- motion of the top 10% of the water - Wind is the major variable affecting this - Deep ocean currents- motion of the bottom 90% of the water - Influence one another intricately - Driven mainly by changes in the density of sea water- called \"Thermohaline circulation\" - Combines to form the \"global conveyor belt\" - Gyres- big loops of ocean currents that form in circles in the Northern and Southern hemisphere - Due to Earth\'s rotational force, forming loop-like patterns - Called the Coriolis effect, disperses heat across the planet