Earth to Class

Core Concepts -- Weather and Climate

1.2e. Earth's early atmosphere formed as a result of the outgassing of water vapor, carbon dioxide, nitrogen, and lesser amounts of other gases from its interior.

1.2f. Earth's oceans formed as a result of precipitation over millions of years.

1.2h. The evolution of life caused dramatic changes in the composition of Earth's atmosphere. Free oxygen did not form in the atmosphere until photosynthetic plants evolved.

1.2g. Earth has continuously been recycling water since the outgassing of water early in its history. This constant recirculation of water at and near Earth's surface is described by the hydrological (water) cycle.

> Water is returned from the atmosphere to Earth's surface by precipitation. Water returns to the atmosphere by evaporation or transpiration from plants. A portion of the precipitation becomes runoff over the land or infiltrates into the ground to become stored in the soil or ground water below the water table.

> The amount of precipitation that seeps into the ground or runs off is influenced by climate, slope of the land, soil, rock type, vegetation, land use, and degree of saturation.

> Porosity, permeability and water retention affect runoff and infiltration. Soil capillarity influences this process.

2.1a. Earth systems have internal and external sources of energy, both of which create heat.

1.1a. Most objects in the solar system are in regular and predictable motion. These motions explain such phenomena as the day, year, and seasons.

2.2a. Insolation (incoming solar radiation) heats Earth's surface and atmosphere unequally due to variations in: intensity (caused by variations in atmospheric transparency and angle of incidence which vary with time of day, latitude, and season); characteristics of the materials absorbing the energy (such as color, texture, transparency, states of matter, and specific heat); and duration, with varies with seasons and latitude.

2.1b. The transfer of energy within the atmosphere, the hydrosphere, and Earth's interior results in the formation of regions of different densities. These density differences result in motion.

2.2b. The transfer of heat energy within the atmosphere, the hydrosphere, and Earth's surface and interior occurs as a result of radiation, convection, and conduction. Heating of Earth's surface and atmosphere by the Sun drives convection within the atmosphere and oceans, producing winds and ocean currents. Density differences are the basis of many Earth phenomena including cloud formation and the formation of atmospheric storms.

2.1c. Weather patterns become evident when weather variables are observed, measured, and recorded. These variables include air temperature; air pressure; moisture (relative humidity and dewpoint); precipitation (rain, snow, hail, sleet, etc.); wind speed and direction; and cloud cover.

2.1d. Weather variables are measured using instruments such as thermometers, barometers, psychrometers, precipitation gauges, anemometers, and wind vanes.

2.1e. Weather variables are interrelated. For example: temperature and humidity affect air pressure and probability of precipitation; air pressure gradient controls wind velocity.

2.1f. Air temperature, dewpoint, cloud formation, and precipitation are affected by the expansion and contraction of air due to vertical atmospheric movements.

2.1g. Weather variables can be represented in a variety of formats including: radar and satellite images; weather maps (including station models, isobars, and fronts); atmospheric cross-sections; and computer models.

2.1h. Atmospheric moisture, temperature and pressure distributions; jet streams, wind; air masses and frontal boundaries; and the movement of cyclonic systems and associated tornadoes, thunderstorms, and hurricanes occur in observable patterns.. Loss of property, personal injury, and loss of life can be reduced by effective emergency procedures.

1.1f. Earth's changing position with regard to the Sun has noticeable effects. Earth revolves around the Sun with its rotational axis tilted at 23.5 degrees to a line perpendicular to the plane of its orbit. During Earth's one-year period of revolution, the tilt of its axis results in changes in the angle of incidence of the Sun's rays at a given latitude. These changes cause variation in the heating of the surface. This produces seasonal variation in climate.

2.1i. Seasonal changes can be explained using concepts of density and heat energy. These changes include: the shifting of global temperature zones, the shifting of planetary wind and ocean current patterns, the occurrence of hurricanes, monsoons, rainy and dry seasons, flooding, severe weather, and ozone depletion.

2.2c. A location's climate (long-term pattern of weather) is influenced by latitude, proximity to large bodies of water, ocean currents, prevailing winds, vegetation, elevation, and topography.

2.2d. Temperature and precipitation patterns are altered by natural events (such as El Nino and volcanic eruptions), and by human influences including deforestation, urbanization, and the production of greenhouse gases, such as carbon dioxide and methane.