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Archive for the 'weather' Category

Map Lightning Strikes With ThunderHunter

Application Name: ThunderHunter

Description: Uses the lightning flash and succeeding thunderclap to map the location of lightning strikes in real time

Publisher’s website: ThunderHunter

Cost: Free

Version/date reviewed: v.1.2  /  8-10-11

Phone/OS: Droid X / Android 2.3

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Android Market (mobile app only)
Android Market (browser)


It’s “monsoon” season here in Arizona, which means that more days than not, there’s a good chance of thunderstorms. ThunderHunter uses the delay in seeing the lightning flash and hearing the thunder to calculate approximately how far away a lightning strike is. If  you point the phone in the direction of the lightning strike, it uses the phone’s built-in compass and GPS to plot the approximate position of the strike.

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Starting up the app gives you the screen above; the compass in the upper right is live, and shows you the approximate compass direction your phone is pointed. When you see a lightning flash, quickly swivel the phone to point in  the direction you saw the lightning hit, and tap the button with the “eye/lightning” icon …

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Now wait for the thunderclap; when you hear it, tap the button with the “ear/lightning” icon …

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Since light travels almost instantaneously, but sound travels much slower (about 300 meters / second), ThunderHunter uses the difference in time between the flash and the thunder to calculate the distance. The arrow icon at lower left returns you back to the first screen, to wait for another lightning flash. The button at lower right takes you to a Google Maps view …

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… where it uses the calculated distance and the orientation of the phone to plot the location of the lightning strike (cloud/lightning icon);  your current position is plotted as the “green man” icon. The GPS will fire up to get your current position,  then turn off to minimize power use. Use the “arrow” button to go back to the previous screen.

Other issues: Don’t worry about not having the phone pointed in the right direction when the lightning hits. ThunderHunter uses the direction you’re facing when you tap the “ear” icon after hearing the thunder, so as long as you point the phone in the direction you saw the lightning before you hear the thunder, the direction and position will be plotted correctly.

Final thoughts: Clean, simple, fun, does what it’s supposed to. Most comparable apps only calculate distance, ThunderHunter goes the extra step and plots the position. Recommended. I will say that if you can see lightning and hear thunder, you should find a safe place to sit out the storm. Lightning can strike without warning as far as 10 miles away from the storm’s central location.




Map Lightning Strikes With Thunderhunter

Application Name: ThunderHunter

Description: Map the approximate position of live lightning strikes.

Publisher’s website: ThunderHunter

Cost: Free

Version/date reviewed: v.1.2  /  7-17-11

Phone/OS: Droid X / Android 2.3

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Android Market (mobile app only)
Android Market (browser)


It’s monsoon season again in Arizona, which means thunderstorms more days than not. You probably know the standard method for estimating how far away a lightning strike is: start counting seconds as soon as you see the lightning flash, stop when you hear the thunder, then divide the number of seconds by 5 to find out how far away the lightning strike was in miles. ThunderHunter automates that process, and adds a twist: if you point your phone in the direction of the lightning flash, it will plot the approximate location of the strike in Google Maps.

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Starting up the app brings you this display. The compass at upper left shows the magnetic direction your phone is pointing in, the “?”  at upper right brings up very minimal help. When you see lightning flash, turn your phone quickly to face in the direction of the lightning, and tap the “eye/lightning” button.

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The button will change to an “ear” icon; when you hear the thunder from the lightning flash, press the button.

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You’ll get an estimate of the distance from the lightning strike in km and miles. Tap on the yellow arrow at lower left to go back to the lightning recording screen; tap on the map …

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… and the app will fire up the GPS to get your current position, then plot the approximate position of the lightning strike, along with your current position (the little green man).

Other issues: Most times, the app will determine direction based on which way the phone is pointing when you hear the thunder. So you can hit the “eye” button when you see a flash in any direction, have time to point the phone at the direction of the flash, then press the “ear” button when you hear the thunder to get an accurate time and direction. On a few occasions, thought, that didn’t seem to work correctly, and it took the direction the phone was facing when the “eye” button was pressed.

Final thoughts: Nifty little app that gives you an approximate distance and location for lightning strikes. Best used indoors at a window, though, since if you can hear thunder and see lightning, you really shouldn’t be outside.




Will There Be Starry Skies In Your Area?

Application Name: Clear Sky Droid

Description: Shows sky clarity and astronomical viewing conditions for nearby areas.

Publisher’s website: Zero Credibility

Cost: Free; $0.99 donation version.

Version/date reviewed: v.1.1.6  /  11-4-10

Phone/OS: Droid X / Android 2.2

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Android Market link (mobile app only)
Android Market link (browser)


If you’re an astronomer interested in whether telescope viewing conditions will be good, a photographer interested in upcoming light conditions, or you just want to know if the skies will be clear for good stargazing, Clear Sky Droid offers an easy way to get this info. The app is a front-end interface to the ClearDarkSky website, where it retrieves the data it displays.

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Figure 1: When you first start up the app, it gets your location from GPS or network data, and shows you a list of monitored locations in your general area, listed by distance from you. You can also search for a specific location, or consult a list of saved favorite locations. Tap on any of the items in the list, and you’ll get the option of adding it to your favorites, showing it on a map, or getting fuller details …

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Figure 2: This is a forecast for the next day or two of what conditions will be like for astronomical viewing. A more detailed description is available here, but basically the top grouping describes the critical factors for good sky conditions, and the darker the square the better the conditions are expected to be.

  • Cloud Cover: How much of the sky is obscured by clouds.
  • Transparency: How clear the sky is; usually reflects the humidity.
  • Seeing: How stable is the atmosphere. Most important if you want to view using a telescope. In poor seeing conditions, the stars will be twinkling a lot as seen by naked eye, but you can still get some decent stargazing in. However, in a telescope, the sky will be jumping around so much that you’ll barely be able to make out any details in faint objects, or fine detail in bright objects like the Moon and planets.
  • Darkness: Usually bad when the sun is up :), but also affected by the moon’s phase and location, and scattering in the atmosphere.

Other Issues: None – no problems.

Final thoughts: Indispensable for the serious amateur astronomer, or the recreational skygazer. For the rest, probably won’t see regular use, but might come in handy on the occasional outdoor trip.




Android Live Wallpaper Of The Earth

Application Name: Earth Live Wallpaper

Description: Animated live wallpaper of Earth and other astronomical bodies, real and imagined.

Publisher’s website: Earth Live Wallpaper

Cost: Free version 1 (donationware); newer version 2 offers faster performance for about $2.75.

Version/date reviewed: v.1.3.9  /  10-31-10

Phone/OS: Droid X / Android 2.2

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Android Market link (mobile app only) – main app
Android Market link (browser)

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Android Market link (mobile app only) – map data
Android Market link (browser)


Note: You should download the app first, then the data. Some Android phones may not support live wallpaper.

Earth Live Wallpaper lets you show an animated image of the Earth as a background in your Android home screens. It also offers options to display other solar system objects like the sun, planets, moons, etc., as well as fictional/imaginary astronomical objects (e.g. planets from the Star Wars universe, Star Trek, Futurama, Avatar, etc.). You also have a huge number of options you can set:

  • Show the moon rotating around the Earth
  • Choose from a variety of background images, and how they’re animated
  • Add an animated starfield
  • Have the globe spin on its axis, rotate freely; interact with you as you swipe
  • And more …

Access the app from the Settings => Wallpaper => Live Wallpaper list, where it’s shown as EarthRot. For real geography, your map choices are:

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Realtime Earth + Clouds => Shows the Earth with actual cloud patterns (updated every 3 hours), and day/night shading with city lights
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Static Earth => Globe image fully lit with an arbitrary cloud pattern
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Earth => Fully lit globe with no clouds
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Earth city lights => Globe at night, with artificial lights from human activity.


I prefer the realtime earth, since it shows up-to-date data like the cloud patterns and night/day terminator line. But it will use about 70 kB of data every time it refreshes the cloud data, which changes every 3 hours or so; that’s close to 17 MB of data in a month, which might be an issue if you’re on a limited data plan.

Issues: None. My phone supports live wallpaper; if yours doesn’t, this wallpaper won’t be terribly useful. Live wallpapers also consume a little bit of extra battery power, so if battery life is a critical issue, you might want to think twice.

Final thoughts: Looks cool, and the realtime Earth view offers useful information. Not an essential app, but if you can live with the slight power drain, worth having.




Animated Radar Precipitation Maps With Radar Now

Application Name: Radar Now

Description: Animated NOAA radar precipitation images, and current weather conditions.

Publisher’s website: Radar Now

Cost: Free (adware)

Version/date reviewed: v.1.0  /  10-4-10

Phone/OS: Droid X / Android 2.2

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Android market link

1/31/11:  App is currently not available on the Android Market.


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Figure 1: Though I generally like the Weather Channel’s Android app, I’ve never been happy with the it’s radar precipitation maps. Detail is too blobby/indistinct, and the animation is often slow to show up.

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Figure 2: Radar Now! uses more detailed precipitation radar maps from NOAA, which show precipitation boundaries and intensity more clearly. I also prefer the background map, showing terrain and hydrographic features like washes, useful in the Southwest where flooding can occur very quickly.. Opening page also includes current weather conditions and your current location, plotted using GPS

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Figure 3: Zoom in for a closer view. Compare that with the Weather Channel radar map at top; it’s not nearly as detailed.

Final thoughts: The Weather Channel app is good for forecasts and multiple locations, and since it’s free, you should definitely have it. But when there’s rain or snow in the forecast, and I want to know if it’s headed my way, Radar Now! is my app of choice.




Android Apps For Hurricane Tracking

As hurricane activity heats up, Android Police has a nice roundup/review of Android apps for monitoring and tracking hurricanes, including maps. Top choices are Hurricane Hub and Hurricane Hound, both free.