Weather Factors Energy in the Earth’s Atmosphere

Energy From the Sun most of the energy in Earth’s atmosphere comes from the sun the energy travels in the form of electromagnetic waves

Energy in the Earth’s Atmosphere Radiation: the direct transfer of energy by electromagnetic waves most of the energy from the sun is in the form of visible light and infrared radiation; a little arrives as ultraviolet radiation

Visible Light: ROYGBIV different colors result from different wavelengths Red/Orange - longest wavelengths Blue/violet - shortest

Energy in the Earth’s Atmosphere Non-Visible Radiation: Infrared Radiation longer than red can be felt as heat

Energy in the Earth’s Atmosphere Ultraviolet Radiation: shorter than violet causes sun burn, skin cancer and eye damage

Energy in the Earth’s Atmosphere Energy in the Atmosphere some sunlight is absorbed or reflected by the atmosphere and the rest passes through to the Earth’s surface

Energy in the Earth’s Atmosphere Energy in the Atmosphere: the ozone layer absorbs most of the ultraviolet radiation water vapor and carbon dioxide (CO 2 ) absorb some infrared radiation.

Energy in the Atmosphere: some sun light is reflected; clouds act as mirrors and reflect energy back into space dust and gases reflect energy in all directions, this is called scattering

Energy in the Atmosphere: blue and violet are scattered more than other colors (shorter wavelengths) Why does the sky look red or orange in the morning and evening?

Energy at the Earth’s Surface: about half of the Sun’s energy is absorbed by the land and water and changed to heat when the Earth’s surface is heated, it radiates most of the energy back into the atmosphere as which type of radiation?

Energy at the Earth’s Surface: most of the infrared radiation from the Earth’s surface cannot make it back into space; this IR radiation is absorbed by the gases (CO 2 and CH 4 ) in the atmosphere heating up the atmosphere

Energy at the Earth’s Surface: These gases form a ‘blanket’ that holds the heat in the atmosphere. This process of holding in the heat is called the greenhouse effect

Heat Transfer Thermal Energy and Temperature Define Temperature Define Thermal Energy

Heat Transfer Temperature Scales Celsius C = 5/9(F-32) Fahrenheit Used in US for weather reporting F= 9/5(C +32)

Heat Transfer How Heat is Transferred Radiation: the direct transfer of energy by electromagnetic waves. the heat you feel from the sun is IR radiation. IR cannot be seen, but can be felt as heat.

Heat Transfer How Heat is Transferred (cont.) Conduction: transfer of heat from one substance to another that is touching. Convection: transfer of heat by the movement of a fluid.

Heat Transfer Heating the Troposphere radiation, conduction and convection work together to heat the Troposphere. the air near the earth’s surface is heated by both radiation and conduction.

Heat Transfer Heating the Troposphere (cont.) only the first few meters of the troposphere is heated by conduction. within the Troposphere heat is transferred mostly by convection The upward movement of warmer are and the downward movement of cool air form Convection Currents.

Winds Wind: is the horizontal movement of air from and area of high pressure to an area of lower pressure. winds are caused by differences in air pressure

Winds Measuring Wind: described by their direction and speed. wind direction is determined by a wind vane. wind speed is measured with an anemometer.

Winds Wind Chill Factor: the wind blowing over your skin removes body heat. The stronger the wind, the colder you feel.

Winds Local Winds: are winds that blow of short distances. caused by the unequal heating of the earth’s surface within a small area. local winds only form when large-scale winds are weak.

Winds Sea Breeze: is a wind that blows from on ocean or lake. Land Breeze: happens at night (reverse of sea breeze) movement of air from land to a body of water.

Global Winds are winds that blow steadily from specific directions over long distances. created by unequal heating of the earth’s surface. occur over large areas

Winds Global Convection Currents: caused by differences in temperatures between the equator and the polles air pressure tends to be lower at the equator and greater at the poles.

Winds Coriolis Effect: the earth’s rotation makes the winds curve. Coriolis Effect Video

Winds Global Wind Belts: the Coriolis Effect and other factors combine to produce patterns of calm areas and wind belts around the earth. Major Wind Belts: Trade Winds Polar Easteries Prevailing Westerlies

Doldrums: near the equator warm are rises steadily and creates area of low pressure air heats and rises too quickly to create much horizontal motion.

Winds Horse Latitudes: Latitude: distance from the equator, measured in degrees. at about 30 degrees north and south the air stops moving toward the poles and sinks; causes another area of calm.

Winds Trade Winds: cold air over the horse latitudes sinks causing area of high pressure. high pressure causes surface winds to blow toward the equator. turned west by Coriolis Effect

Trade Winds (cont.) winds in the northern hemisphere between 30 degrees and the equator blow from the northeast. winds in the southern hemisphere between 30 and equator blow from southeast.

Winds Prevailing Westerlies: located in mid-latitudes (between 30 and 60 north and south) blow towards the poles and westerly direction due to Coriolis Effect. important to weather of the USA

Winds Polar Easterlies: cold air near poles sinks and moves toward lower latitudes Coriolis Effect shifts winds to the est

Winds Jet Streams: about 10 km above earth’s surface bands of high speed winds 100’s of km wide, but not very deep generally blow from west to east mph travel around the globe and wander nother and south in wavy path.

Water in the Atmosphere

Water in the Atmosphere Humidity is the measure of the amount of water vapor in the air. how much water vapor air can hold depends on its temperature warm air holds more water vapor than cool air

Water in the Atmosphere Relative Humidity is the percentage (%) of water vapro that is actually in the air compared to the maximum amount of water vapor the air can hold at a particular temperature Example: at 10 C, 1 cubic meter of air can hold 8g of water vapor. If there are actually 4g of water, the relative humidity would be 50% Relative Humidity of 100% is said to be saturated

Water in the Atmosphere How Clouds Form clouds from when water vapor condenses to form liquid water or ice crystals as water cools, the amount of water vapor it can hold decreases causing the water vapor to condense. Dew Point: temperature at which condensation begins. If the dew point is below freezing, the water vapor may change directly into ice crystals.

Water in the Atmosphere The role of Particles tiny particles must be present so water has a surface on which to condense. salt crystals, dust and smoke Liquid water that condenses onto solid surfaces si called dew. Ice that has been deposited on a surface that is below freezing is called frost.

Water in the Atmosphere Types of Clouds types of clouds is based on their shape and altitude. Cirrus wispy, feathery form only at high altitudes (above 6 km) made of ice crystals

Water in the Atmosphere

Types of Clouds (cont.) Cirrocumulus clouds look like rows of cotton balls. often indicate that a storm is coming

Cumulus Clouds look like fluffy, rounded piles of cotton less than 2 km above ground may grow in size and height and extend upward as much as 18 km if they are not tall this indicates fair weather. tall, towering cumulus clouds are called Cumulonimbus, often produce thunderstorms

Water in the Atmosphere

Types of Clouds (cont.) Stratus Clouds form in flat layers usually cover all or most of the sky dull, gray color may produce drizzle, rain or snow (called nimbstratus)

Water in the Atmosphere

Types of Clouds (cont.) Altocumulus Alto means ‘high’ mid-level cumlus (between 2 and 6km) Altostratus mid-level stratus higher than regular stratus, but lower than cirrus and other ‘high’ clouds

Types of Clouds (cont.) Fog clouds that form at or near ground level form when ground cools after a warm, humid day in mountainous areas, fog can form as warm, moist air moves up the mountain slope and cools most common in areas near bodies of water or low-lying marshy areas.

Precipitation Types of Precipitation Rain drops of water are called rain if they are at least 0.5 mm in diameter smaller drops are called drizzle water of even smaller drops is called mist Drizzle and mist usuallyfall from stratus clouds

Precipitation Sleet raindrops that fall through air with temp below 0 C causing drops to freeze into particles of ice Ice particles smaller than 5mm in diameter is called sleet

Freezing Rain rain drops that fall through a layer of air below 0 C close to the ground and freeze when they touch a cold surface

Precipitation Snow water vapor in a cloud that is converted directly into ice crystals. Hail Round pellets of ice larger than 5 mm are called hailstones only form inside cumulonimbus clouds

Precipitation Drought long periods of unusually low precipitation Measuring Precipitation snowfall is measured 2 ways: use of a simple measuring stick or melting snow and measuring how much water it produces 10cm of snow contains about 1cm of rain Rain Measurements rain is measured using a rain gauge.

Precipitation The End