Weather Part I Weather Variables 2 23 16

Weather – Part I- Weather Variables 2 -23 -16

Definitions • Meteorology- is the study of the atmosphere- including weather. Weather-the daily conditions of the atmosphere. It can change from time to time and place to place. Climate- the type of weather an area has over a long period of time.

Layers of the atmosphere • Layers of the atmosphere: separated by difference of temperature patterns.

Troposphere Gases present In Troposphere We live in the troposphere. • 0 -12 km • Temperature decreases • All weather occurs here • All water vapor in the atmosphere is here • Contains people, clouds, airplanes

Other layers Stratosphere • Temperatures increase • Home of the Ozone layer. • 12 -50 km • Mesosphere • Upper layers- temperatures get colder (coldest layer) • The air is very thin here. • Where meteors will burn up Thermosphere • 82 -600 km • Gets very hot as you go up • Contains aurora borealis • Sub layers: ionosphere, and exosphere

Northern Lights • Aurora borealis happens in ionosphere. Aurora Borealis is also called the Northern Lights. They happen when sun rays enter ionosphere and hit the moving molecules. This is sometimes called magnetic storm. What we see is a glow in many colors.

Mount Everest

Things that change in atmosphere • Temperature • Water content and humidity • Air pressure • Cloud Cover • Wind Speed • Precipitation

Temperature • Measures the average kinetic energy (energy of motion) of molecules. • Heat enters atmosphere from the sun as incoming solar radiationinsolation

Thermometer- instrument used to measure air temperature • Fahrenheit – Water freezes at 32° – Water boils at 212 ° • Celsius – Water freezes at 0 ° – Water boils at 100 ° • Kelvin – Water freezes at 273 K – Water boils at 373 K

Temperature Conversions

Isotherm- line connecting locations of equal temperature

Connecting Isotherm lines

Air Pressure • Caused by weight of the air • Weight of the air above earth’s surface pushes down on the surface so there is pressure exerted on the surface

Air pressure • Air pressure is greatest • Why are we not closer to the surface of crushed by air the earth pressure? • Average pressure is 14 • Ans: air pressure is pounds (lbs. ) per pushing out at the square inch same time it is pushing in

Factors affecting air pressure: • 1. Elevation(altitude)- the higher the elevation the lower the air pressure (air is thinner- less weight is pushing down) • 2. Temperature- warmer the air, lower the pressure • 3. Moisture/Humidity- more water vapor that goes into the air, the lower the air pressure

Effects of Air pressure- Altitude Sickness • Altitude sickness (mountain sickness) is an illness that ranges from a mild headache and weariness to a life-threatening build-up of fluid in the lungs or brain at high altitudes. • Acute altitude sickness is the mildest and most common form. A more serious form of altitude sickness is high altitude edema (HAPE). This illness occurs when fluid builds up within the lungs, a condition that can make breathing extremely difficult. Usually, this happens after the second night spent at a high altitude, but it can happen earlier or later. HAPE often comes on quickly. If left untreated, it can progress to respiratory collapse and ultimately to death. HAPE is the number one cause of death from altitude sickness. • Another severe form of altitude sickness is high altitude cerebral edema (HACE), in which fluid builds up within the brain. As the brain swells with fluid, the person's mental state changes. Loss of coordination, coma, and, finally, death can follow unless the problem is recognized and treated promptly.

Effects of Air pressure. Decompression sickness • high-pressure gases in the air come in contact with water, they dissolve into the water. This is how carbonated beverages are made. To make carbonated water, water is exposed to highpressure carbon dioxide gas, and the gas dissolves into the water. We all know what happens when you release the pressure in a bottle of soda -- bubbles suddenly start rising. The gas dissolved in the water at high-pressure comes out of the liquid when the pressure is released, and we see it as bubbles.

Measuring air pressure • Barometer- an instrument used to measure changes in air pressure 1. Mercury barometer

Measuring air pressure • 2. Aneroid barometer • Measured in millibars= average 1013 mb • Range- 970 - 1040 mb

Moves clockwise and outward WEATHER CONDITITIONS High- cool, clear Dry, sunny Low- warm, cloudy wet Moves counterclockwise And inward

Pressure Conversions HIGH 1013. 2 LOW

Isobars- lines connecting patterns of equal air pressure

Example:

Isotherms v. Isobars • Isotherms – Can be lines or – Generally DOES circles-can end in NOT end in the middle of the circles. map – ALWAYS goes – Intervals of 4 from one side of – Would have a H or the U. S. to the L inside the center other IN BOTH, YOU CANNOT CROSS LINES!!!!

Wind- the movement of air parallel to the ground • Caused by differences in air pressure and temperature

Winds move from high to low pressure

Draw the lines around a High and a Low H L

Wind- Closer the isobar lines, faster the wind speed

Wind instruments • Wind vane- measures wind direction • Anemometer- measures wind speed

Wind direction • Winds are named for the direction that they come from • On a map direction is shown with a line showing where it came from.

Sea Breeze- Day • Water has a high Air sinks over water and moves to land specific heat= takes longer to warm up and cool down • Air over water is cooler, so it sinks and a breeze moves from water to land

Land Breeze- Night • At night , the land will cool down faster than the water- the breeze then moves from land to sea

Relative Humidity • The amount of water • It is expressed in %. in the air is called • 100% is full and can't humidity. hold any more. • The ability of air to hold water changes • Water gets into the air depending on the by - evaporationtemperature. (liquid to gas) • Relative humidity – or sublimation- solid to gas tells "how full" the air is with water.

Dew Point • To get the water out of the air it either condenses or sublimes. • condense-changing from gas to liquid. - dew • Dew Point- the temperature at which condensation begins At this point- condensation can begin and clouds will start forming

What is dew? • Dew is liquid water droplets that form on grass, spider webs and other things in the early morning or late evening. Dew only forms under certain conditions. • If a warm, clear day is followed by a cool, clear evening, dew will likely form. On a normal warm day, water evaporates from the warm ground into the air. That means it turns from a liquid into a gas called “water vapor. ” • When evening comes, the warm ground continues to radiate heat into the air. As the ground begins to cool, the air will not be able to hold all the moisture. • At a certain point — a temperature called the “dew point” — water vapor in the air will begin to condense (turn back to liquid water) faster than water is evaporating. • When this happens, dew forms on surfaces that aren’t warmed by the heat radiated from the ground. That’s why you mainly see dew on things like grass, leaves and even car roofs. • - See more at: http: //wonderopolis. org/wonder/why-is-the-grass-wet-in-themorning/#sthash. f. PSw. Of. Th. dpuf

What is frost? If the temperature gets low enough in the evening, dew may undergo yet another transformation. When temperatures are low enough, dew may freeze to a solid form that we then call “frost. ” – See more at: http: //wonderopolis. org/wonder/why-isthe-grass-wet-in-themorning/#sthash. f. PSw. Of. Th. dpuf

Measuring Relative Humidity & Dew Point • The “Dry Bulb” - It is just a thermometer. – It measures the air temperature. • The “Wet Bulb” – Has a little wet booty tied to the bottom. – Gets cool when water evaporates. Instrument: Sling psychrometer

• In order for anything to happen: – the sun must heat the earth which heats the air above it and rises into the atmosphere.

Clouds- how they form • Form by process called condensation – This happens when the air is so moist that it can no longer hold any water. – = air is saturated

• As air rises, it cools because of expansion and moving away from heat source • Air will then cool enough to reach dewpoint • Water vapor then condenses onto condensation nuclei • When enough droplets condense- we see them as clouds

Why clouds look different • Clouds are usually a mixture of both water vapor droplets and ice crystals. The water and ice scatter all light, making clouds appear white. If the clouds get thick enough or high enough all the light above does not make it through, hence the gray or dark look. Also, if there are lots of other clouds around, their shadow can add to the gray or multicolored gray appearance.

Orographic Lifting

When air is forced to rise because it hits mountains, it will expand, cool, and condense - Windward side of the mountains will have a cool, moist climate. - Leeward side- there will be a warm, dry climate Windward Leeward

Wind speed- measured in knots

Station models. Converting air pressure • Converting from millibars to station model code – use only the last three digits and throw out the decimal point – Example: 1020. 5 = 205 • Converting from station model to millibars – if the code is 500 or higher put a 9 in front, otherwise put a 10 and put decimal point in front of last number – Example: 281= 1028. 1

DO NOW: 1 st column- convert to station model code /2 nd column convert to millibars • 1008. 4= • 987= • 976. 6= • 888= • 1022. 2= • 168= • 992. 2= • 080=

When air is forced to rise because it hits mountains, it will cool and condense On the Leeward side, there will be a dry climate that is usually warmer than the windward On the Windward side of the mountains it will have a moist climate.