Question:

How can I find a good color palette for my plot?

Examples:

! Plot sst
     USE coads_climatology
     SET REGION/L=1
     SET VIEW ul
     FILL/NOLABELS/PALETTE=ocean_temp sst; GO land

! plot temperature minus mean with a centered palette
     SET VIEW UR
     FILL/NOLABELS/PALETTE=white_centered sst - sst[x=@ave,y=@ave]; GO fland

! use a greyscale paletete
     SET VIEW LL
     FILL/NOLABELS/PALETTE=greyscale sst; GO land

! plot a relief map using the land_sea palette
     USE etopo120
     SET VIEW lr 
     FILL/NOLABELS/PALETTE=land_sea rose

Explanation:

See the Ferret Users Guide Commands Reference section 20 (palettes), and Chapter6, section 5.2 (palette creation) for more on specifying a palette with the plot commands, and about the different kinds of palettes.  There is also a Palette demo about the different kinds of palettes.

Also see the FAQ, How can I produce a plot with both colors and patterns? for an example using the pattern fill and shade keys, and Got any good ideas for black & white graphics? for a discussion of filled plotting using black and white palettes and patterns.

Here is a table showing the available palettes. For the Percent palettes, the script "go try_palette palette_name" has been used to make the examples.  This shows the palette at several different resolutions. The Levels and Values palettes are shown with examples from datasets to point out their advantages.
 

Palette name	Description	Type of Palette	Example Plot
default	The default palette; range through a rainbow of colors	percent
ocean_temp	Shows range of ocean temperature by value, so plots with different ranges of values will have the same colors for given temperatures. These two plots are the same except for the region.	value
rainbow_by_levels	A variety of colors assigned by level: each level gets one color. The LEVELS qualifier is used to specify six levels for the first plot and eighteen for the second.	level
rainbow	The same as "default"	percent
rnb	The same as "default"	percent
rnb2	Another rainbow of colors	percent
saz2	Yet another rainbow of colors	percent
light_rainbow	Similar to rainbow, but with washed-out lighter colors	percent
broad	Designed to distinguish levels over a broad range	percent
dark_land_sea	For topography/ bathymetry plots. Brown and green on land, blue for sea	percent
land_sea	A lighter palette for topography/ bathymetry plots	percent
ocean_blue	A range of blues for bathymetry plots	percent
dark_terrestrail	A range of green and brown for topography plots	percent
terrestrial	A lighter palette for topography plots.	percent
modulo	A palette whose colors on either end match	percent
no_blue	Palette with no blue tones	percent
no_green	Palette with no green tones	percent
no_red	Palette with no red tones	percent
low_blue	Palette with low ammount of blue	percent
low_green	Palette with low ammount of green	percent
low_red	Palette with low ammount of red	percent
centered	Distinguishes values above and below the middle level; warm colors above and cool colors below.	percent
white_centered	Another centered palette with white as the central color	percent
no_blue_centered	Another centered palette with no blue tones	percent
no_green_centered	Another centered palette with no green tones	percent
no_red_centered	Another centered palette with no red tones	percent
grayscale (also greyscale)	Series of grays	percent
inverse_grayscale  (and inverse greyscale)	With high and low reversed	percent
bluescale	Series of blues	percent
inverse bluescale	With high and low reversed	percent
greenscale	Series of greens	percent
inverse_greenscale	With high and low reversed	percent
redscale	Series of reds	percent
inverse_redscale	With high and low reversed	percent
Single colors black blue, blue_light, blue_dark brown, brown_light, brown_dark cyan, cyan_light, cyan_dark gray, gray_light, gray_dark grey, grey_light, grey_dark green, green_light, green_dark magenta, magenta_light, magenta_dark orange, orange_light, orange_dark pink, pink_light, pink_dark purple, purple_light, purple_dark red, red_light, red_dark tan, tan_light, tan_dark violet, violet_light, violet_dark white yellow, yellow_light, yellow_dark	One color in the palette.  These are useful for colorbars, filling between curves, making backgrounds, and filling polygons to make different colored dots on a plot, as in marking station locations. For examples see the FAQ: How can I fill between two curves? and the Ferret v5.6 release notes	percent	poly/over/line/pal=pink xpts,ypts,,square poly/over/line/pal=orange_dark xp,yp,,circle