Univariate Choropleth

http://people.cas.sc.edu/hardistf/research.htm

Univariate choropleth maps are maps that only display data about one variable. The variable is expressed with colors or symbols in which case the color can vary in shades due to an increase or decrease in its value. In this map the areal data is divided by county areas. Only hues of blue are used in this map but null values and overlapping can occur which "mixes" colors. I am not sure what this map is displaying but it is using shades of blue to depict percent population in relation to another property such as ethnicity, age, or gender. I believe dark areas and "white" areas are values of either 0% or 100%, respectively.

Bivariate Choropleth

http://www.personal.psu.edu/acr181/election.html

Bivariate choropleth maps are used to display and compare two sets of data and combines two different sets of graphic colors. These maps can portray two different sets of variables at the same time on the map. Its main purpose is to display the spatial distribution of the variables along with its geographical concentration. Overlapping of data can occur between the two variables. In this case their is an arbitrary legend that displays these colors. The map above is a comparison between the percent votes for Sen. John Kerry and the individual counties population in the 2000 elections.

Unclassed Choropleth Map

http://www.esds.ac.uk/international/support/user_guides/gisoverview.asp



Unclassed Choropleth maps portray areal data without the use of classes. Instead of using classes this style of map contains as many intervals as there are areal units. This type of choropleth map allows small changes in data to be displayed under its own color. It uses a color ramp or scale to measure the changes. With the amount of data sometimes being overwhelming, it is possible that this style of map is sometimes hard for the viewer to distinguish between areas containing different values. This map is showing the infant mortality rate, per 1000 live births, in Europe compared to Italy. Darker colors have a higher mortality rate than lighter colors in the "brown" section. Blue areas are countries that have a lower infant mortality rate than Italy.

Classed Choropleth Maps

http://www.alignstar.com/support/clients/webhelpv5/About_choropleth_maps.htm

Choropleth maps typically use data ranges and graduated color shading. Data is collected and spread out over a certain interval, coinciding with a specific color palette. This data is compiled and focuses on a single theme, such as population, with data summarized to a particular geographic level such as States, Counties or ZIP Codes. The above map is an analysis of a population density within a land area, notably counties. It clearly conveys its message through a monochromatic color scheme, where darker areas are more highly populated than lighter shades of green. This map is classed because a specific color or shade is assigned to a specific set of values.

Range Graded Proportional Circle Map

http://personal.frostburg.edu/krtopping0/maps.htm

Range graded proportional circle maps consists of data mapped with a circle instead of a dot. These maps are a type of point pattern analysis maps. The sizes of the circles relates to a measured variable, not the area over which it is measured. In this type of map, range graded, there is only a set number of circle sizes used. These sizes usually correlates to a specific amount of measured data. The map above uses range grading to show the number of people killed in road accidents in parts of Europe.

Continuously Variable Proportional Circle Map

http://www.quicktopic.com/blog/

(see post: a better election map-population centers)

Continuously variable proportional circle maps are point pattern maps where the point data is mapped with a circle and not a dot. The size of the circle relates to a measured variable, not the area over which it is measured. All circles that are not equal in measured data can vary in size, their is not a set number of circles sizes used. The map above uses this technique to measure and display data about population centers, or areas with a greater population density. 

Isopleth: Isotherm (temperature) Map

http://www.middleschoolscience.com/isotherms.htm

Isopleths are contour lines that depict a certain variable which cannot be measured at a specific point. They must be calculated from data that is collected over an area. Examples of these are Isobars (air pressure), Isotachs (thickness), and Isohyets (rainfall). They are displayed using contour lines where connecting points of the line have the same "amount" of measured data. Above is an example of an Isotherm (temperature) map of the US during a specific period. It also uses shading to differentiate between different areas of temperature change.

Isopach: Thickness of geological stratum

http://seeps.geol.ucsb.edu/pages/isopach.html

An isopach is an isoline that connects points of equal thickness of a geological stratum formation or group of formations. It can be used to display a measure of thickness to a variety of different objects or materials. Above, isopachs are used to display the relative thickness of sediment on the ocean floor near oil rigs. Both isolines and color shading are used to convey the thickness.

Isohyets: Rainfall

http://www.scoop.co.nz/stories/AK0808/S00090.htm

Isohyets are lines on a map that connect points of an equal amount of rainfall in a given period. They can be studied to find places and or times when the rainfall is greatest, and can give a prediction of future flooding. The map above shows average rainfall during one month in a province of New Zealand. These types of maps are also called isohyetal maps.

Isotachs: Wind Speed

http://www4.ncsu.edu/~nwsfo/storage/cases/20040908/

Isotachs are contour lines drawn a map that distinguish areas of equal wind speeds. They are used to analyze wind speeds primarily in the upper atmosphere such as the jet stream. From this along with other types such as Isobars, future weather patterns can be predicted. The map above was information compiled about hurricane Frances as is passed over the eastern U.S. The red solid lines represent the isotachs.

Isobars: Air pressure

http://www.weatheronline.co.uk/reports/wxfacts/Isobars-on-surface-maps.htm

Isobars are contour lines on a map that shows equal or constant pressure relating to that line. They are lines drawn on a map joining places of equal atmospheric pressure. They can be used to predict future weather patterns and are widely used to do so. The map above uses isobar contour lines of different color (red and blue) to show both high and low pressure, respectively. 

LIDAR: Light Detectin and Ranging

http://coralreefs.wr.usgs.gov/mapping_lidar.html

LIDAR systems can be used in airborne devices to extract highly detailed images of a surface. This is an remote sensing technology that measures the distance to a target by illuminating it with laser light in pulses. It is basically a laser-range finding system used to create images. From the data collected a 3-D image can be created. In the image above, the SHOAL system created an image of a reef tract. Colors closer to blue indicate a greater depth within the water and red indicated a lesser depth. It can only be used in this fashion from the air when used in shallow depths. The image above is showing the different depths of a reef off the coast of Hawaii. It also shows where the reef begins creating a shelf and a "hole" in the reef.

Doppler Radar

http://kwilklab.wordpress.com/2011/04/15/polarimetric-doppler-radar-rocks-the-house/

Doppler radars are very important to meteorologists because it can accurately view the motion of a weather system. This can lead to future predictions of the weather system, such as if it might later form tornadoes. This specific type of radar works by beaming a microwave signal at an object, and by using the doppler effect, it can produce velocity data about the object from a distance. It is mainly used to produce atmospheric profiles of weather systems (clouds) such as its motion and composition. This system is a form of active radar where events can be viewed in real time. The above still image is from a polarimetric doppler radar which can  differentiate between horizontal and vertical components of an object. This image shows the intensity of a storm by use of color shading passing through southern Florida. The closer to red the color is the more intense the storm is.